Control device for controlling a plurality of image forming apparatuses

ABSTRACT

A control system for collectively supervising a plurality of copiers or similar image forming apparatuses connected to a control device by communication lines with or without the intermediary of communication control units. To down-load data relating to image formation, the control device determines whether or not a copier of interest is an inoperative state and, if it is in an inoperative state, automatically sends the data to the copier via a telephone line, an exchange, and a communication control unit. This data is written to storing means built in the copier. To up-load data relating to image formation, the control device causes each copier to automatically send the data stored in the storing means thereof and stores the data in memory means thereof. Up-loading is effected at an optimal time other than the time when the copier is performing an automatic adjustment, in use, or quite likely to be used.

This is a Division of application Ser. No. 08/327,420 filed on Oct. 21,1994, now U.S. Pat. No. 5,510,876, which is a Divisional, of applicationSer. No. 08/069,350 filed on May 28, 1993, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a control system for collectivelysupervising a plurality of copiers or similar image forming apparatusesconnected to a control device by communication lines with or without theintermediary of communication control units.

In a control system for the above application, copiers or similar imageforming apparatuses are connected to a control device located at aservice station by telephone lines or similar communication lines, asdisclosed in, for example, Japanese Patent Laid-Open Publication Nos.257155/1990, 259666/1990, and 196053/1991. By collectively controllingthe remote image forming apparatuses by the single control device orhost machine, it is possible to totalize the conditions in which eachapparatus is used and to use the supervisory data for the maintenance ofthe apparatus. The conditions in which the image forming apparatus isused include the number of copies produced. On the other hand, thecontents of maintenance include an automatic call origination to thecontrol device resulted from the self-diagnosis of the image formingapparatus, and the adjustment of various sections of the apparatusexecuted by an access from the control device. These data can even besent to, for example, the service station as image data implemented by afacsimile function. In the event of addition or version-up of a program,each image forming apparatus may receive the program from the controldevice or host machine and writes it therein, or at the time ofmaintenance the host may send guide data indicative of an operationprocedure to the image forming apparatus in matching relation to theoperating condition of the apparatus, as also proposed in the past.

Japanese Patent Laid-Open Publication No. 64770/1991, for example,teaches a control system in which a transmitting device is interposedbetween the communication line and the control device and selectivelyoperable in a communication mode or in another mode. When the controldevice sends a data send request to a copier, the transmitting deviceoperates in the communication mode only if the copier is not reproducinga document.

Further, assume that the line is busy when an error, for example, is tobe sent from the copier to the control device. Then, data representativeof the error is held until the line being monitored becomes ready. Incase of emergency, a communication under way is forcibly ended by arelay circuit so as to send the emergency to the control device.Moreover, a particular time zone is allocated to each of the checking ofthe copier and the transmission of data to the host; the latter iseffected in a time zone in which the line is not frequently occupied.

It is a common practice with modern copiers to accurately adjust datafor image formation copier by copier at the time of shipment, so thateach copier may produce attractive images from the beginning wheninstalled at the user's station. Since the data generated at the time ofshipment are stored copier by copier, a serviceman can readily readjustthe copier by referencing the data in the event of an error or defectiveimage, when data stored in the copier are destroyed, or at the time ofreplacement of a developer or a photoconductive element. This reducesthe load on the serviceman and allows the copier to recover in a shortperiod of time.

When the developer or the photoconductive element is replaced, it issometimes desirable to restore all the data of the copier to theirinitial conditions, rather than to readjust the data one by one. In thelight of this, a copier having a memory clearing function has also beenproposed.

However, the problem with the conventional control system is that theserviceman has to down-load the data of the copier from the controldevice or up-load the data of the copier to the control device. Theup-loading and down-loading operations still pose a substantial load onthe serviceman. Moreover, since the data cannot be supervised withoutresorting to manual operations, it is likely that the up-loadingprocedure is omitted by accident.

A copier with multiple functions available today allows various initialmodes to be selectively set up to the user's taste when the power sourceof the copier is turned on. For example, an arrangement may be made suchthat while in the standard specifications the first sheet cassette isautomatically selected out of a plurality of cassettes on the turn-on ofthe power source, the second sheet cassette can be selected on anoperational panel. Also, a buzzer may be muted as desired by the user.However, in the conventional control system, a serviceman has to setsuch conditions by manipulating the operation panel at the time ofdelivery. This increases the load on the serviceman as the number offunctions increases.

The drawback with the copier of the type having a memory clearingfunction is that since the initial data stored in all the copiers areidentical, the serviceman has to readjust necessary data at the cost oftime. The serviceman may inquire the service station the initial datagenerated at the time of delivery or may operate the operation panel toread them out of the control device. Although this may reduce theadjustment time, the load on the serviceman is still heavy. Moreover,since the data cannot be supervised without resorting to manualoperations, it is likely that the up-loading procedure is omitted byaccident.

Assume the control system of the type setting up a communication modeonly when the image forming apparatus is not forming an image, asmentioned earlier. Even with this type of system, it is likely that thedata representative of adjusted image forming conditions are destroyedsince the system allows the image forming apparatus to communicate withthe control device by an interruption when the apparatus isautomatically adjusting the image forming conditions. The automaticadjustment includes the adjustment of a lamp voltage for reducing thecontamination of the background, i.e., automatic VL correction.

When a communication is held between the image forming apparatus and thecontrol device in parallel with the automatic adjustment of the imageforming conditions, a CPU (Central Processing Unit) built in theapparatus is driven hard, lowering the processing speed. Although such aproblem may be eliminated if the control method is complicated, thiscannot be done unless the software is changed, resulting in an increasein cost.

Assume that the control device generates a communication request whilethe automatic adjustment of image forming conditions is under way, andpriority is given to communication by interrupting the adjustment. Then,after the communication, the adjustment interrupted halfway has to beexecuted all over again. This forces the operator to await the end ofthe automatic adjustment, wasting additional several minutes. Further,if the image forming apparatus begins to communicate with the controldevice when a person intends to use the apparatus, the person has towait until the communication ends.

Assume that the image forming apparatus communicates with the controldevice when user-oriented special modes are being set on the apparatus.Then, when data is rewritten by communication processing, the modesbeing set are sometimes invalidated. For example, when a data rewritecommunication for cancelling an automatic sheet select mode is effectedwhile a program mode (special mode) including an automatic sheet selectmode is being entered, the mode being entered is invalidated due to thedifference in sheet select mode. In such a case, the mode has to be setall over again after the communication, preventing the apparatus frombeing used just after the communication.

In the control system wherein a number of copiers or similar imageforming apparatuses are connected to a control device located at, forexample, a service station by communication control units or dataterminals and telephone lines or similar communication lines, thecommunication control units usually associated with the image formingapparatuses each controls the communication with the control device.When the communicable condition of the image forming apparatus andcommunication control unit changes, e.g., when a change from a connectedstate to a disconnected state occurs, the apparatus detects an error,generates a serviceman call, and stops the operation. Although a changefrom the disconnected state to the connected state may occur while theoperation of the apparatus is stopped, the apparatus does not becomeusable unless manipulated by a serviceman. This type of system,therefore, cannot adopt an expedient in response to a change in theconnection condition of the apparatus and communication control unit, sothat the operation efficiency available with the system is limited.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a controlsystem for an image forming apparatus which reduces the load on aserviceman and eliminates erroneous operations in the event ofdown-loading data relating to image formation from a control device tothe image forming apparatus or up-loading data from the latter to theformer.

It is another object of the present invention to provide a controlsystem for an image forming apparatus which allows a person to use theapparatus without waiting a long time.

It is another object of the present invention to provide a controldevice for an image forming apparatus which is efficiently operable inresponse to a change in the connection condition of the apparatus and acommunication control unit.

In accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,storing means for storing data relating to image formation, and atimepiece for setting an operative state or an inoperative state of atleast part of the image forming apparatus in terms of time. The controldevice comprises second communicating means for communicating with theimage forming apparatus, and rewriting means for reading the state ofthe timepiece and rewriting data stored in the storing means when thepart of the image forming apparatus is in the inoperative state.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,storing means for storing data relating to image formation, and waitingmeans for setting a waiting state when the image forming apparatus isunable to operate. The control device comprises second communicatingmeans for communicating with the image forming apparatus, and rewritingmeans for reading the state of the image forming apparatus and, if theimage forming apparatus is in the waiting state, rewriting the datastored in the storing means.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,first storing means for storing data relating to image formation, anddeciding means for determining the state of the image forming apparatus.The control device comprises second communicating means forcommunicating with the image forming apparatus, second storing means forstoring data relating to image formation, and transmitting means forsending the data stored in the second storing means to the image formingapparatus via the second communicating means on the basis of the resultof decision made by the deciding means.

Also in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,first storing means for storing data relating to image formation, andobject sensing means for sensing an object present at a side where theimage forming apparatus is to be manipulated. The control devicecomprises second communicating means for communicating with the imageforming apparatus, second storing means for storing data relating toimage formation, transmitting means for transmitting the data stored inthe second storing means to the image forming apparatus via the secondcommunicating means, and inhibiting means for inhibiting thetransmitting means from operating when the object sensing means sensesan object.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisingfirst communicating means for communicating with the control device, andfirst storing means for storing data relating to image formation. Thecontrol device comprises second communicating means for communicatingwith the image forming apparatus, second storing means for storing datarelating to image formation of the apparatus, and control means forreading the data out of the first storing means of the apparatus todetermine whether or not the apparatus has just been delivered to theuser's station and causing, when the apparatus has just been delivered,the second storing means to store the data read out of the first storingmeans.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,first storing means for storing data relating to image formation, andmeans for reading the data out of the first storing means to determinewhether or not the apparatus has just been delivered to the user'sstation and, if the apparatus has just been delivered, sending adelivery signal to the control device. The control device comprisessecond communicating means for communicating with the image formingapparatus, second storing means for storing data relating to imageformation of the apparatus, and control means for reading, on receivingthe delivery signal, the data out of said first storing means of theapparatus and storing the data in the second storing means.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,first storing means for storing data relating to image formation, andmeans for reading the data out of the first storing means to determinewhether or not the apparatus has just been delivered to the user'sstation and, if the apparatus has just been delivered, sending adelivery signal and the data read out of the first storing means to thecontrol device. The control device comprises second communicating meansfor communicating with the image forming apparatus, second storing meansfor storing data relating to image formation, and control means forstoring, on receiving the delivery signal, the data relating to imageformation and sent from the apparatus in the second storing means.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisingfirst communication means for communicating with the control device, andfirst storing means for storing data relating to image formation. Thecontrol device comprises second communicating means for communicatingwith the image forming apparatus, second storing means for storing datarelating to image formation of the apparatus, and means for reading thedata out of the first storing means of the apparatus to determinewhether or not the image forming apparatus has just been delivered tothe user's station and, if the apparatus has just been delivered,reading the data out of the second storing means to thereby rewrite thedata of the first storing means.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesfirst communicating means for communicating with the control device,first storing means for storing data relating to image formation, andmeans for clearing the data of the first storing means and sending cleardata to the control device. The control device comprises secondcommunicating means for communicating with the image forming apparatus,second storing means for storing data relating to image formation of theapparatus, and means for reading, on receiving the clear data, the dataout of the second storing means and storing the data in the firststoring means.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprisesautomatic adjusting means for automatically adjusting image formingconditions, and inhibiting means for inhibiting, if the apparatus isforming an image or the automatic adjusting means is adjusting imageforming conditions when a communication request is received from thecontrol device, the apparatus from communicating with the controldevice.

Also, in accordance with the present invention, in a control system forcontrolling at least one image forming apparatus connected to a controldevice by a communication line, the image forming apparatus comprises ahuman body sensor for sensing a human body approaching the apparatus,and inhibiting means for inhibiting the apparatus from communicatingwith the control device when the human body sensor senses a human body.

Further, in accordance with the present invention, in a control systemfor controlling at least one image forming apparatus connected to acontrol device by a communication line, the image forming apparatuscomprises mode selecting means for selecting an image forming mode, moderegistering means for registering the image forming mode, and inhibitingmeans for inhibiting the apparatus for communicating with the controldevice when the mode registering means is registering the image formingmode.

Furthermore, in accordance with the present invention, in a controlsystem for controlling at least one image forming apparatus connected toa control device by a communication control unit and a communicationline, the image forming apparatus comprises determining means fordetermining whether or not the image forming apparatus is communicablewith the communication control unit.

Moreover, in accordance with the present invention, in a control systemfor controlling at least one image forming apparatus connected to acontrol device by a communication control unit and a communication line,the image forming apparatus comprises a communication permit switch forallowing the apparatus to communicate with the communication controlunit.

In addition, in accordance with the present invention, in a controlsystem for controlling at least one image forming apparatus connected toa control device by a communication control unit and a communicationline, the image forming apparatus comprises determining means fordetermining whether or not the apparatus is communicable with thecommunication control unit, a communication permit switch for allowing acommunication of the image forming apparatus with the communicationcontrol unit, first control means for selectively validating orinvalidating a communication of the apparatus and communication controlunit in response to data from the determining means and data from thecommunication permit switch, and second control means for determiningwhether or not to cause the determining means to determine whether theapparatus is communicable with the communication control unit inresponse to data from the determining means and data from thecommunication permit switch.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription taken with the accompanying drawings in which:

FIG. 1 is a block diagram schematically showing a control systemembodying the present invention and applicable to an image formingapparatus;

FIG. 2 shows a copier which is a specific form of the image formingapparatus used in the embodiment;

FIG. 3 shows a glass platen included in the copier of FIG. 2 and variouspatterns adjoining it;

FIG. 4 shows part of the copier of FIG. 2 joining in the control oftoner concentration;

FIG. 5a-5c are diagrams representative of a relation between the outputof a photosensor or P sensor included in the copier and representativeof a P sensor pattern formed on a photoconductive drum and the output ofthe sensor representative of the background of the drum;

FIG. 6 shows a lamp provided on a first scanner included in theembodiment together with a light control arrangement;

FIG. 7 shows the first scanner in detail;

FIG. 8 shows various potentials to be deposited on the surface of thedrum;

FIG. 9 is a graph indicative of a relation between the variouspotentials of the drum and the density of a document;

FIG. 10 shows a specific layout of an operation panel provided on thecopier;

FIG. 11 is an enlarged view of a pattern display included in theoperation panel;

FIG. 12 is a block diagram schematically showing control circuitryincluded in the copier shown in FIGS. 1 and 2;

FIG. 13 is a block diagram schematically showing a specific constructionof a communication control unit of FIG. 1;

FIG. 14 is a block diagram schematically showing a specific constructionof a control device of FIG. 1;

FIG. 15 is a schematic block diagram for describing a down-loadingoperation to occur in the inoperative condition of the copier;

FIG. 16 is a schematic block diagram for describing a down-loadinterruption preventing operation to occur in the inoperative conditionof the copier;

FIG. 17 is a schematic block diagram for describing the destination ofdown-load data;

FIG. 18 is a schematic block diagram for describing a down-loadinterruption preventing operation to occur in the operative condition ofthe copier;

FIGS. 19A-19B are flowcharts demonstrating a specific operation of thecommunication control unit of FIG. 1;

FIG. 20 is a table listing control codes and data;

FIG. 21A and 21B show respectively the format of information codes ofFIG. 20 and the contents of numerals of first and second levels;

FIGS. 22A-22D show respectively the contents of numerals of third tosixth levels;

FIGS. 23A-23B are flowcharts demonstrating the operations of the copierand control device at the time of reception;

FIGS. 24A-24B are flowcharts associated with FIGS. 23A-23B;

FIG. 25 is a flowchart representative of a control program of thecontrol device;

FIGS. 26-38 each shows a particular picture to appear on the display ofthe control device;

FIG. 39 is a flowchart indicative of the operation of the copier at thetime of delivery;

FIG. 40 is a flowchart indicative of the operation of the control deviceat the time of delivery;

FIG. 41 is a flowchart representative of a modified operation of thecontrol device at the time of delivery;

FIG. 42 is a flowchart representative of the initial mode set control ofthe control device;

FIGS. 43A and 43B are flowcharts demonstrating the memory clearprocedure of the copier;

FIG. 44 is a default data table;

FIG. 45 shows set data;

FIG. 46 is a data code table;

FIG. 47 is a block diagram schematically showing an alternativeembodiment of the present invention;

FIG. 48 is a flowchart demonstrating a main routine to be executed by aCPU shown in FIG. 12;

FIG. 49 is a flowchart representative of part of usual mode processingof FIG. 48 which relates to a communication with the control device;

FIG. 50 is a flowchart representative of an automatic VL adjustmentprocedure also included in the usual mode processing;

FIG. 51 is a flowchart representative of human body sense processing tobe executed by the CPU of the copier in another alternative embodimentof the present invention;

FIG. 52 is a flowchart representative of processing relating to acommunication with the control device in the embodiment;

FIGS. 53-55 are flowcharts each demonstrating another processing alsorelating to a communication with the control device;

FIGS. 56 and 57 are flowcharts each being representative of specificprocessing relating to a communication with the control device to beexecuted by the CPU of the copier in still another embodiment of thepresent invention;

FIG. 58 is a block diagram schematically showing yet another alternativeembodiment of the present invention;

FIG. 59 is a block diagram schematically showing a specific constructionof a communication control unit of FIG. 58;

FIG. 60 is a block diagram schematically showing a control device ofFIG. 58;

FIG. 61 is a block diagram schematically showing specific controlcircuitry built in the copier of FIG. 58;

FIG. 62A-62C each shows a specific communication sequence relating toremote information particular to the embodiment;

FIGS. 63A-63C each shows a specific communication sequence relating tothe access of the control device to the copier;

FIGS. 64A-64C each shows a specific communication sequence relating tothe access of the control device to the communication control unit;

FIG. 65 shows a communication sequence in which the communicationcontrol unit accesses the copier without using the control device;

FIGS. 66A-66B list parameters to be set in the communication controlunit of FIG. 59;

FIGS. 67A-67C show specific formats of communication data to be sent byremote information;

FIG. 68 shows a specific data format for read processing which is one ofthe accesses of the control device to the copier shown in FIG. 60;

FIG. 69 shows a specific data format for write processing;

FIG. 70 shows a specific data format for execute processing;

FIG. 71A-71C show specific data formats with which the control deviceaccesses the communication control unit;

FIG. 72 shows a specific data format for the communication control unitto access the copier;

FIG. 73 is a flowchart demonstrating a main routine to be executed bythe CPU of the copier for information control;

FIGS. 74-76 are flowchart each demonstrating a particular subroutineincluded in the main routine of FIG. 73;

FIG. 77 is a flowchart representative of a main routine which the CPU ofthe copier executes in response to an access from the communicationcontrol unit;

FIG. 77-80 are flowcharts each demonstrating a particular subroutineincluded in the main routine of FIG. 77;

FIG. 81 shows a communication sequence to occur in an idle state whenfive copiers are connected to the communication control unit;

FIG. 82 shows a communication sequence to occur when a text to betransmitted by remote information is present at a copier designated byan address 2;

FIG. 83 shows a communication sequence for sending a test representativeof the result of information from the communication control unit to acopier designated by an address 5;

FIG. 84 is a flowchart representative of a communication modedetermining procedure to be executed by the CPU of FIG. 61;

FIG. 85 is a flowchart representative of a connection detectionprocedure of FIG. 84; and

FIG. 86 is a flowchart representative of a switch OFF subroutine of FIG.84.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 2, an image forming apparatus to which the presentinvention is applicable is shown and implemented as anelectrophotographic copier operable with plain paper sheets (sometimesabbreviated as PPC hereinafter). As shown, the copier, generally 1, hasa body 2, an automatic document feeder (ADF) 3 mounted on the top of thebody 2, a manual insertion tray 4 and a mass sheet feeder 5 operativelyconnected to one side of the body 2, and a copy tray 6 mounted on theother side of the body 2. A document tray 7 is included in the ADF 3 andprovided with a document set sensor 8. Accommodated in the copier body 2are a scanner section 10, an image forming section 1, a sheet feedingsection 12, a fixing and discharging section 13, an inverting section14, a two-sided copy unit 15, etc.

The scanner section 10 is made up of a first scanner 24 having a glassplaten 21, a lamp 22 and a first mirror 23, a second scanner 27 having asecond mirror 25 and a third mirror 26, a third scanner 30 having afourth mirror 28 and a fifth mirror 29, a sixth mirror 31, and lens 32.

The image forming section 11 includes a photoconductor drum 35. Arrangedaround the drum 35 are a quenching lamp 36, a main charger 37, an eraser38, a potential sensor 39, a developing unit 40 to accommodate a tonercartridge 41, a pretransfer charger 42, a transfer charger 43, aseparation charger 44, a photosensor or P sensor 45, a cleaning unit 46.A register roller pair 47 is located on a sheet transport path just infront of an image transfer position while a transport belt 48 isarranged behind the transfer position.

In the sheet feeding section 12, a first to a fourth tray 51, 52, 53 and54 are removably disposed, and each is loaded with paper sheets ofparticular size. A first to a fourth sheet feed units 55, 56, 57 and 58are respectively associated with the trays 51-54 for feeding sheets fromthe tray. Also, a manual insertion/mass feed unit 59 is shared by themanual insertion tray 4 and mass sheet feeder 5. A mass sheet feed tray(LCT) 60 is accommodated in the mass sheet feeder 5.

A right, a left and a horizontal transport section 61, 62 and 63,respectively, are provided to transport the sheets selectively fed fromthe sheet feed units 55-59 and two-sided copy unit 15. A fixing unit 65and a discharge roller group 66 are arranged in the fixing anddischarging section 13 while a turn-over roller group 67 is arranged inthe inverting section 14.

In operation, the drum 35 supported by a shaft, not shown, is rotated ina direction indicated by an arrow A in the figure by, for example, acopy command. A document is fed by the ADF 3 to the glass platen 21 andthen illuminated by the first scanner 24. The resulting reflection fromthe document is focused onto the drum 35 via the first mirror 23, secondmirror 25, third mirror 26, lens 32, fourth mirror 28, fifth mirror 29,and sixth mirror 31. The drum 35 has been uniformly charged by the maincharger 37 beforehand. As a result, the reflection from the documentelectrostatically forms a corresponding latent image on the drum 35. Theeraser 38 illuminates needless portions of the latent image to match itto a paper sheet or a projection image. To reproduce the document imagein a ×1 magnification, the drum 35 and first scanner 24 are driven atthe same speed. The developing unit 40 develops the latent image with atoner to produce a corresponding toner image. At this instant, apotential (bias voltage) may be applied to the developing unit 40 toincrease or decrease the density of the image, as desired.

A sheet is fed form any one of the trays 51-54, manual insertion tray 4,mass feed tray 60 and two-sided copy unit 15 by associated one of thesheet feed units 55-59 at a predetermined timing. The sheet is drivenalong the right transport path 61, left transport path 62 or horizontaltransport path 63 to the register roller pair 47 which is held in a haltthen. Subsequently, the register roller pair 47 is driven at such atiming that the leading edge of the sheet meets that of the toner imageformed on the drum 35. Then, the pretransfer charger 42 and transfercharger 43 transfer the toner image from the drum 35 to the sheet. Sincethe surface of the drum 35 is extremely smooth, the separation charger44 lowers the potential and, therefore, the electrostatic adhesion ofthe sheet.

The sheet carrying the toner image is separated from the drum 35 by aseparating member, not shown, and then conveyed to the fixing unit 65 bythe transport belt 48. The fixing unit 65 fixes the toner image on thesheet by heat and pressure. Thereafter, the sheet or copy is driven outof the copier to the copy tray by the discharge roller group 66. In atwo-sided copy mode, for example, the sheet is once driven into theinverting section 14, turned over, fed to the two-sided copy unit 15,and again fed from the unit 15 toward the image forming section 11.After the image transfer, the cleaning unit 46 removes the tonerremaining on the drum 35 with a brush and a cleaning blade thereof, andthen the quenching lamp 36 uniformizes the surface potential of the drum35.

The various timings stated above are controlled by a control circuit,which will be described, mainly on the basis of pulses synchronous tothe rotation of the drum 35 or reference pulses for driving the drum 35.

FIG. 3 shows the glass platen 21 and its neighborhood in a plan view.There are shown in the figure, an optical table 121, a photosensorpattern or P sensor pattern 122, and ADS reference pattern 123, a VLpattern 124, and a VD pattern 125. The p sensor pattern 122, ADSreference pattern 123, VL pattern 124 and VD pattern 125 are provided onthe underside of the optical table 121.

A reference will be made to FIG. 4 for describing a toner concentrationcontrol procedure particular to the copier 1. To begin with, the firstscanner 24 is brought to a position below the P sensor pattern 122. Areflection from the P sensor pattern 122 is focused onto the surface ofthe drum 35 having been uniformly charged by the main charger 37. Then,the developing unit forms a corresponding toner image on the drum 35.The resulting toner image or P sensor toner image is read by the Psensor 45. Assume that the output voltage of the P sensor 45 associatedwith the P sensor toner image (P sensor output voltage) is Vsp, that theP sensor output voltage associated with the background of the drum 35 isVsg, that a value 1/13 Vsg resulted from the comparison of Vsp and Vsgis a reference voltage, and the toner concentration is adequate when Vspis the reference voltage. When Vsp is greater than 1/13 Vsg, the tonerconcentration is determined short and a toner is supplemented. FIGS.5A-5C show such a relation between Vsp and Vsg.

FIG. 6 shows the lamp 22 of the first scanner 24 together with a lightquantity control system associated therewith. There are shown in thefigure a sensor 130 responsive to the light from the lamp 22, a maincontrol board 131, and a stabilizer 132. Specifically, the quantity oflight from the lamp 22 has to be maintained adequate at all times toinsure the stable formation of a latent image on the drum 35. For thispurpose, the sensor 130 senses the quantity of light form the lamp 22and delivers its output to the main control board 131. In response, themain control board 131 causes the stabilizer 132 to change a lamp outputsignal, thereby controlling the quantity of light from the lamp 22.

The first scanner 24 is shown in detail in FIG. 7. An automatic densityset (ADS) control procedure will be described with reference to FIG. 7.While the lamp 22 scans the document, an ADS sensor 133 continuouslyreads the resulting reflection from the document. The highest outputvoltage of the ADS sensor 133 is compared with a reference value whichwill be described. Then, the bias voltage for development is changed onthe basis of whether VDE is high (light) or low (dark) so as to maintaina constant image. The output of the ADS sensor 133 to appear when theADS reference pattern 123, FIG. 3, is illuminated by a predeterminedquantity of light is the above-mentioned ADS reference value.

Referring to FIGS. 8 and 9, process control to be executed by the copier1 will be described. Generally, the potential of a latent image changesdue to the aging of the lamp 22, contamination of the optics (mirrors,lens, etc.), change in the output of the main charger 37, changes in thesensitivity and residual potential of the drum 35, etc. The processcontrol senses a change in the potential of a latent image by use of thepotential sensor 39 and feeds it back to the charging, exposing anddeveloping processes, so that a stable image may be formed at all times.Stabilizing a latent image is also successful in stabilizing the tonerconcentration control implemented with the P sensor 45.

As shown in FIG. 8, the quenching lamp 36 illuminates the surface of thedrum 35, and then the main charger 37 uniformly charges it. Let thepotential deposited on the drum 35 by the main charger 37 be referred toas a postcharge potential V0. Also, let a potential derived from theillumination of the VL pattern 124, FIG. 3, and a potential derived fromthe illumination of the VD pattern 125, FIG. 3, be called a white areapotential VL and a black area potential VD, respectively. Further, apotential resulting from the illumination of the drum 35 by the eraser38 will be referred to as a residual potential VR.

The process control will be described with reference to FIG. 9. Toproduce an adequate image, it is necessary that the difference betweenthe black area potential VD and the white area potential VL bemaintained constant. Although the residual potential VR cannot bereduced to zero even when the quantity of light is increased, it ispossible to maintain the potential difference constant by adding VR tothe target values of the potentials VD and VL. Although the residualpotential VR uniformly increases the surface potentials by VR, theincrease in surface potential can be compensated for if VR is also addedto the bias for development.

FIG. 10 shows a specific arrangement of an operation panel provided onthe copier in a plan view. As shown, the operation panel, generally 70,has a guidance display 71 and a pattern display 72 each beingimplemented by a liquid crystal display. A number of keys are positionedat the right and left and at the front of the operation panel.Specifically, a start key 73, an interrupt key 74, a preheat key 75, amode clear/preheat key 76, numeral keys 77, a clear/stop key 78, a timerkey 79, a program key 80, an enter key 81, and a guidance key 82 arearranged at the right-hand side. A remote inform key 83, a sorter key84, a two-side key 85, a page continuous key 86, a delete key 87, asheet-oriented magnification change key 88, zoom keys 89, a margin key90, a center key 91 and a size-oriented magnification change key 92 arearranged at the left-hand side. Further, a reduce key 93, an enlarge key94, a ×1 key 95, a sheet select key 96, an automatic sheet select key97, density adjust keys 98, and an automatic density key 99 are locatedat the front of the intermediate area. When the remote inform key 83 isturned on to effect a communication, an indicator in the form of an LED83a glows.

FIG. 11 shows the pattern display 72 in an enlarged view. As shown, thepattern display 72 includes a pattern D1 indicative of the number ofcopies set, a pattern D2 indicative of the number of copies produced, apattern D3 indicative of a running state, a pattern D4 indicative ofdensity, a pattern D5 indicative of a misfeed position, a pattern D6requesting sheet supplement, a pattern D7 indicative of a misfeed, apattern D8 indicative of a remote communication error, a pattern D9requesting toner supplement, a pattern D10 indicative of remainingamounts of sheets, a pattern D11 indicative of sheetselection/size/direction, and a pattern D12 indicative of amagnification.

The guidance display 71, FIG. 10, displays messages for operation andwarning. The operation panel 70 is characterized in that the remoteinform key 83 allows the user to hold a communication for requesting aservice, and in that the error indicator D8 informs the operator of aremote communication error. If desired, the exclusive remote inform key83 may be replaced with a particular order in which other keys arepressed or a particular duration of depression.

Referring again to FIG. 1, a control system embodying the presentinvention locates a control device or host machine 141 at a servicestation and connects to a plurality of copiers or PPC 1 by telephonelines 142 and exchanges 143. The user's stations are each provided witha communication control unit (CCU) 144. The copier 1 is connected to theCCU 144. A telephone set 145 and a facsimile apparatus, can also beconnected to the CCU 144. The CCU 144 is inserted in the existingsubscriber line.

How data are interchanged in the control system will be describedhereinafter. To begin with, data is down-loaded from the control device141 to the copier 1, as follows. The control device 141 sends a copieridentification code or ID code, a control code and control data to theCCU 144. If the control code is meant for the CCU 144, the CCU 144executes processing based on the received data; if it is meant for thecopier 1, the CCU 144 sends the control code and control data to aparticular copier 1 designated by the ID code. The copier received thecontrol code and control data performs a corresponding operation. Toup-load data from the copier 1 to the control device 141, it sends an IDcode, an occurrence code and occurrence data to the CCU 144. On settingup the line, the CCU 144 sends the collected data to the control device141.

FIG. 12 is a block diagram schematically showing control circuitryincorporated in the copier 1. As shown, the control of the copier body 2is mainly executed by a CPU 100 on the basis of control programs anddata stored in a ROM (Read Only Memory) 101. A RAM (Random AccessMemory) 102 stores interim data to occur during processing. Acommunication interface (IF) unit 103 interfaces the copier 1 to the CCU144, i.e., receives control code and data from the CCU 144 in the eventof sending data of the copier 1 to the CCU 144. An analog-to-digitalconverter (ADC) 104 receives a voltage to be applied to the lamp 22, anemission voltage for the P sensor 45 and a voltage representative ofreceived light, an output of the potential sensor 39, an output of theADS sensor 133, an output of the sensor 130, an output of a drum currentsensor responsive to a current to flow through the drum 35, an outputvoltage of a thermistor included in the fixing unit 65, and so forth.

An IN port 105 receives the outputs of various keys provided on theoperation panel 70, FIG. 10, a memory clear dip switch (DIPSW), a remotecommunication permit/inhibit dip switch (DIPSW), and a human body sensor114 which is a kind of object sensors. Provided on the front end, e.g.,the front cover of the copier 1, the human body sensor 114 senses ahuman body or an object approaching the copier 1. For example, thissensor 114 may be implemented by a pyroelectric infrared ray sensor or athermocouple type infrared ray sensor using a thermoelectromotive force.The remote communication permit/inhibit dip switch permits or inhibitsthe communication with the CCU 144, FIG. 1. An OUT port 106 producesdisplay control data meant for the displays and indicators of theoperation panel 70 shown in FIGS. 10 and 11.

An optics control unit 107 controls the scanner section 10, FIG. 2. Ahigh-tension power source unit 108 applies a high voltage to each of themain charger 37, separation charger 44, transfer charger 43 andpretransfer charger (PTC) 42 and applies a bias voltage to a developingroller included in the developing unit 40. A motor control unit 109controls a main motor for driving the drum 35 and various rollersincluded in the sheet feed units and transport sections. A heatercontrol unit 110 controls the current supply to a heater received in thefixing roller of the fixing unit 65, so that the surface temperature ofthe fixing roller may remain in a predetermined range. A printer controlunit 111 delivers copier control data to a printer. A sensor sensitivitycontrol unit 112 changes the light reception gains of the sensors 130,133 and 45 as well as the emission voltage for the LED of the sensor 45.A timer 113 indicates time and is used to ON/OFF control an AC powersource by a weekly timer.

When the memory clear dip switch is in an ON state in the event of theturn-on of a power source, the contents of a RAM (or nonvolatile memory)backed up by a battery BT are replaced with predetermined values. Remotecommunication control is executed only if the remote communicationpermit/inhibit dip switch is in an ON state in the event of the turn-onof the power source. The surface temperature of the fixing roller isdetermined in terms of the output voltage of the thermistor of thefixing unit 65. When this temperature is lower than predetermined one,the copying operation is inhibited.

FIG. 13 shows a specific configuration of the CCU 144, FIG. 1. Thecontrol of the CCU 144 is mainly effected by a CPU 181 on the basis ofcontrol programs and data stored in a ROM 182. A RAM 183 is used tostore internal data to occur during processing. The CPU 181 has thefollowing functions:

(1) To collect data of the copier 1 via an associated interface (IF)circuit 184 and send it from a modem 185 to the control device 141 viathe exchange 143 and telephone line 142, FIG. 12;

(2) To receive a control code and data from the control device 141 viathe telephone line 142 and exchange 143 with the modem 185 and send themto the copier 1 via the IF circuit 184;

(3) To send a control signal to an AC power source control unit 186included in the copier 1 via the IF circuit 184 so as to ON/OFF controlthe power supply;

(4) To distinguish a plurality of copier which may be connected to theCCU 144 and to arbitrate remote communications thereof; and

(5) To switch the communication with the control device 141 and theordinary conversation on the telephone set 145 with the modem 185.

The communication between the CCU 144 and the copier 1 is effected via acommunication interface by serial communication of parallelcommunication.

FIG. 14 shows a specific construction of the control device 141. Asshown, the control device 141 has a host computer 161 for executingvarious kinds of processing, a memory 162 for storing control data andother data, a cathode ray tube or similar display 163 for displayingvarious pictures which will be described, operating means in the form ofa keyboard 164, a printer 165 for outputting control data, a telephoneset 166, and a modem 167 for communicating with the user's copier overthe telephone line 142.

The contents of the RAM 102 of the copier or PPC 1 shown in FIG. 12should not be rewritten while an operation is under way. The statuses inwhich the RAM 102 should not be rewritten are as follows:

    ______________________________________                                        Status 1:                                                                             when the drum 35 is in a stop                                                  ...data relating to processes rewritable                             Status 2:                                                                             when the heater of the fixing unit is OFF                                      ... fixing temperature allowed to be set                             Status 3:                                                                             waiting state                                                                  ... modes other than operation mode rewritable                       Status 4:                                                                             jam                                                                            ... part of process data and operation mode rewritable               Status 5:                                                                             fault                                                                          ... part of programs rewritable                                      Status 6:                                                                             inoperative state                                                              all rewritable except for program code of                                     communication IF 103                                                 ______________________________________                                    

In the inoperative state of status "6", the minimum power sourcenecessary for a communication to begin is in an ON state. At thebeginning of a communication, the AC power source control unit 186.FIGS. 1 and 13, controlled by the CCU 144 turns on a necessary powersource to allow most of the data in the RAM 102 to be rewritten.Typically, the status "6" occurs when the weekly timer is in the OFFstate.

How to rewrite the contents of the RAM 102 is as follows. As shown inFIG. 15, the control device 141. FIG. 1, reads an operation status flagF1 stored in the RAM 102 and relating to the statuses "1" to "6" via thetelephone line 142, CCU 141 and communication IF 187. When the read dataF1 is indicative of the status "6", i.e., when the weekly timer is in anOFF state, the control device 141 down-loads to a predetermined addressof the RAM 102 the data of the copier 1 stored in the memory 162, FIG.14, at the time of delivery or the modification of the copier 1. At thisinstant, all or part of the data stored in the RAM 102 is rewritten.

It may occur that simply reading the operation status flag F1 does notsatisfy the rewriting condition for the following reason. Usually,several seconds to several ten minutes is necessary for data to bedown-loaded over a communication line. Should the weekly timer be turnedon during such a period of time, the status would shift to, for example,the status "3" and cause the copier 1 to start operating, interruptingthe down-loading.

To eliminate the above problem, as shown in FIG. 15, the illustrativeembodiment reads out the past power ON/OFF time data stored on aweek-day or date basis and the current time of the timer 113. Only ifthe down-loading procedure will complete before the weekly timer turnson the power source, the embodiment starts on the down-loadingprocedure. This decision uses the timer 113 of the copier 1 since theweekly timer is subordinate to the timer 113. Another approach toprevent the down-loading from being interrupted is that the controldevice 141 prevents the weekly timer from being turned on. Thisalternative approach may be implemented as any one of the followingthree methods:

Method 1: To read the current time of the timer 113 and then stop thetimer 113, corrects the period of time consumed to return the time tothe stored time after down-loading, write the current time as if thetimer 113 was continuously operating, and then start on the operationagain;

Method 2: To read and store the next ON tome data of the weekly timerand, at the same time, write in the weekly timer the time data delayedby a down-loading time, and then return the stored ON time data to theweekly timer after down-loading; and

Method 3: As shown in FIG. 16, to provide the RAM 102 anin-communication flag F2 beforehand, set the flag F2 on the start ofdown-loading, and reset it after down-loading. As the weekly timer isturned on, the CPU 100 of the copier 1 checks the in-communication flagF2 and, if it is set, inhibits the transition to another status.

Therefore, by any one of the above methods "1" to "3", it is possible toprevent down-loading from being interrupted even when the weekly timerreaches an ON time while down-loading is in progress.

FIG. 17 shows another specific memory configuration which includes anonvolatile RAM 102a and a D-RAM 102b in addition to the ROM 101. TheROM 101 stores a communication IF program, down-load bootstrap programand other basic programs. Backed up by the battery BT, the RAM 102astores process control set data, operation mode set data, etc.Alternatively, the basic programs may be partly stored in the ROM 101and partly in the RAM 102a. The D-RAM 102b stores a fault diagnosisprogram or similar program for executing a different kind of processingfor a moment, while implementing a temporary work area for dataprocessing.

The memory 162 of the control device 141. FIG. 14, stores a particulartype of machine and a particular ID code associated with each of thecopiers 1. Data matching set data and program particular to each copier1 are selectively down-loaded to the RAM 102a and D-RAM 102b.

A procedure to occur in the waiting status "3" will be described. Asshown in FIG. 15, the control device 141 reads the status flag F1relating to the statuses "1" to "6". If the flag F1 is indicative of thestatus "3", the control device 141 down-loads, among the data stored atthe time of delivery or the modification of the copier 1, predetermineddata except for the operation mode to a predetermined address of the RAM102. As shown in FIG. 18, a heater 652 is accommodated in a fixingroller 651 included in the fixing unit 65. When the heater 652 is in anON state, the control device 141 down-loads predetermined data otherthan the set temperature. It is to be noted that the range to bedown-loaded depends not only on the operation status flag but also onthe presence/absence of peripheral equipment, environmental conditions,and the type of the machine.

It is likely that down-loading is interrupted even in the waiting status"3". The status "3" is usually cancelled as the fixing roller 651 isheated to a predetermined temperature. Hence, pressing the start key 73.FIG. 10, on the cancellation of the status "3" brings about thefollowing problems. Assume that the start key 73 is pressed when datarelating to image formation sent from the control device 141 are beingwritten to the RAM 102, interrupting the down-loading. Then, an imagewill be formed before all the image forming data have been transferred,resulting in a defective copy. For example, when the potential of thedrum 35 and the bias voltage for development are not transferred incombination, a defective copy will be produced due to an inadequatepotential. Moreover, assume that the start key 73 is pressed when thecontrol device 141 is sending the set values of the control modeparticular to the copier 1, interrupting the down-loading. Then, thecopier 1 will perform an operation not expected by the user or theserviceman.

In the light of the above, as shown in FIG. 18, the control device 141determines an expected reloading time D3 of the copier 1 incommunication, e.g., a temperature D2 of the fixing roller 65 via athermistor 653, and then estimates the remaining period of time in whichthe set temperature will be reached on the basis of a relation betweenthe time and the temperature elevation rate. Only if the down-loadingwill complete within the remaining period of time, the control device141 starts on the down-loading.

Alternatively, to prevent down-loading from being interrupted in thewaiting status "3", the control device 14 may execute control such thateven when the status "3" is cancelled, the transition to the next statusis inhibited, as follows. Specifically, as shown in FIG. 18, the RAM 102is provided with an in-down-load flag F3 beforehand. On the start ofdown-loading, the control device 141 sets the flag F3 and, after thedown-loading, resets it. As the waiting state "3" is cancelled, the CPU100 of the copier 1 checks the flag F3 and, if it is set, inhibits thetransition to the next status.

Assume that the copier 1 has a weekly timer, but a time is not set inthe timer. Then, the inoperative status "6" will not be reached forever.In this embodiment, down-loading can be effected by any one of thefollowing methods:

Method 1: At the time of delivery of the copier 1, the serviceman entersdata particular to the copier 1 in the control device 141 so as toup-load them to the copier 1. These data include time data of a weeklytimer and allow the control device 1 to see that a time is not set inthe weekly timer before a communication. In such a case, a time is setby setting up down-loading in the waiting status.

Method 2: Down-loading in the waiting status is restricted regarding thedata which can be rewritten. Hence, a command is sent to the copier 1 toset the inoperative status "6" or the time data is rewritten to set itup, and the down-loading is effected.

In this way, the embodiment down-loads data in matching relation to thewaiting status "3" or the inoperative status "6" each having aparticular restriction. This prevents down-loading from beinginterrupted and, in addition, reduces the load on the serviceman.

Some copiers, e.g., inexpensive copiers lack the weekly timer and the ACpower source control unit 186 to be controlled by the CCU 144.Down-loading is effected with this kind of copier, as follows. When thecontrol device 141 calls the copier 1 via the telephone line 142 and CCU144, it can see the ON/OFF state of the power source of the copier 1,depending on whether or not the copier 1 returns and answer or whetheror not a carrier signal is present. Based on the result of decision, thecontrol device 141 may execute any one of the following three differenttypes of down-loading.

Type 1: When the power source of the copier 1 is in an ON state, thecontrol device 141 effects down-loading in matching relation to thewaiting status "3" or the inoperative status "6"; when the former is inan OFF state, the device 141 continuously monitors the power source and,on the turn-on of the power source, effects down-loading.

Type 2: A drawback with the type 1 is that when the power source is OFF,the communication rate increases due to the continuous monitor. Toeliminate this drawback, the control device 141 monitors the powersource intermittently and, on the turn-on of the power source, effectsdown-loading.

Type 3: Even the type "2" increases the communication rate due to theintermittent monitor and, in addition, increases the load on the controldevice 141. In the light of this, a memory for temporarily holdingdown-loaded data and a communication control function for emulatingdown-loading are incorporated in the CCU 144. The communication controlfunction can be implemented by use of the RAM 183. FIG. 13 a s memoryand by storing a down-loaded program in the ROM 182 beforehand. Thecontrol device 141 once down-loads data to the CCU 144, causes the CCU144 to monitor the power source of the copier, and effects down-loadingon the turn-on of the power source.

A reference will be made to FIGS. 19-46 for describing the communicationbetween the control device 141, the CCU 144, and the copier 1 in detail.

To begin with, the control device 141 sends a copier ID code, controlcode and data while the copier 1 sends a control code and data, asstated earlier. In the meantime, the CCU 144 is operated as will bedescribed with reference to FIGS. 19A-19B.

As shown in FIGS. 19A-19B, in steps S1-S3, while the CCU 144 does notreceive no data from the copier 1 or the control device 141, the CCU 144reads the history data of jam, number of copies, operation time anderror, function data, division-by-division data and other data at apredetermined time set in the timer thereof beforehand and stores themin the RAM 183, FIG. 13. Therefore, the control device 141 can up-loadsuch data even when the power source of the copier 1 is OFF.

When the CCU 144 receives data from either of the copier 1 and controldevice 141 in the step S1, it determines whether or not the data hasbeen sent from the control device 141 (S4). If the result of thisdecision is negative, N, the CCU 144 determines that the data is fromthe copier 1, generates a copier ID code out of the received IF circuit184. FIG. 13, and then adds the ID code to the data (S5). Subsequently,the CCU 144 sends the received data with the ID code to the controldevice 141 (S6). If the data has been received from the control device141 as determined in the step S4, the CCU 144 determines a copier IDcode (S7) to identify a copier with which the control device 141 is tohold a communication. Then, the CCU 144 determines whether or not thereceived data is requesting the read-out of data stored in the RAM 183(S8). If the answer of the step S8 is positive, Y, the CCU 144 sends thedata of interest to the control device 141 in place of the copier 1(S9). If the answer of the step S8 is negative, the CCU 144 activatesonly the IF circuit 184 associated with the copier 1 of interest (S10)and then sends the received data to the IF circuit 184 (S11).Subsequently, the CCU 144 determines whether or not the reception hasended (S12) and, if the answer if positive, disconnects the line and IFcircuit 184 (S13).

The communication between the control device 141 and the copier 1 is asfollows. The copier ID code will not be described specifically since itis dealt with by the CCU 144. As shown in FIG. 20, the control code anddata are made up of an information code having eleven bytes, the numberof data having two bytes, data extending over the indicated number ofbytes, and an end code having one byte. In the event of communication,the control code and data are implemented by ASCII code. The informationcode indicative of the contents of data is arranged according topredetermined rules shown in FIGS. 21A, 21B and 22A-22D. These rulesapply to both the transmission from the copier 1 to the control device141 and the transmission from the control device 141 to the copier. FIG.21A shows the format of the information code while FIG. 21B shows thecontents of numerals belonging to the first and second levels of theinformation code. FIGS. 22A-22D show respectively the contents ofnumbers belonging to the third to sixth levels of the information code.

Some specific examples will be described with reference to FIG. 20. Toread the operation time of the copier 1, the control device 141 sends aninformation code "14070010101" and the number of data "0" to thecopier 1. On receiving the number of data "0", the copier 1 returns tothe control device 141 the same information code, the number of data"4", and four bytes of operation time data. To mute a buzzer disposed inthe copier 1, the control device 141 sends an information code"51050080101" and the number of data "1" to the copier 1. The copier 1waits until one byte of data has been fully received, rewrites a memoryMDBZ storing a buzzer mode corresponding to the information code tostore the received data, and then returns the same information code andthe number of data "0" to the control device 141. As a result, when akey input expected to cause the buzzer to sound is entered, the copier 1mutes the buzzer by referencing the memory MDBZ.

Further, a wild card "*" can be used as an information code.Specifically, the information codes are represented by serial numericalvalues when their contents are analogous. Hence, to read all the datarelating to the weekly timer, for example, the control device 141 sendsan information code "5105302****" and the number of data to thecopier 1. In response, the copier 1 decodes the information code andthen sends data corresponding to consecutive information codes"51053020000" to "51053029999" to the control device 141. However,regarding an information code which is absent in the copier 1, thecopier 1 does not return any data. For example, in FIG. 20, since"51053001000" and other information codes are absent, the copier 1returns data associated only with "51053020101, "51053020201","51053020301", 51053040101" and "51053020501". The wild card "*" isavailable only in the event of reading and has the number of data "0".

To call all the data set in the copier 1, the control device 141 uses aninformation code "51*********". As shown in FIG. 21B, the numeral "5" ofthe first level of the information code indicates set data or similardata which can be written and read. When the first level is "5", thesecond level is "1", and the rest is the wild card "*", then the copier1 decodes such an information code, reads memory data corresponding toinformation codes "51000000000" to "51999999999", and then returns allthe information codes present and the number of codes to the controldevice 141.

The control device 141 causes the copier 1 to perform a given operationby use of an information code whose first level and second level are "7"and "1", respectively. For example, with such an information code, thecontrol device 141 may cause the copier 1 to test the main charger, mainmotor and other loads independently or in combination, to train thefixing unit, or to perform a procedure for setting up adequate imageforming conditions.

Since a single information code includes two bytes of data, more thanninety-nine data cannot be sent. Assume that more than ninety-nine datashould be continuously sent, e.g., a program should be up-loaded ordown-loaded. Then, as shown in FIG. 21B, while the read and writeinformation code is "9" at the first level and "1" at the second level,the third and successive levels thereof are so set as to indicate theblock of a program to be sent, as an exception. For example, when oneblock has sixty-four bytes, an information code "91000000000" and thenumber of data "64" may be sent and followed by sixty-four bytes fromthe sixty-fourth byte of the program. Information codes whose firstlevel is "5" and second level is "2" or "3" are also available for thetransfer of data.

A reception procedure which applies to both the control device 141 andthe copier 1 will be described with reference to FIGS. 23A-23B and24A-24B. A transmission procedure is not illustrated since it simplysends, in the event of reading, an information code of data to read andthe number of data "0" while sending, in the event of writing, aninformation code of data to write, the number of data, and data.

As shown in FIG. 23A-23B, in steps S21-S29, an information code, thenumber of data, and data are inputted. Regarding the steps S23-S26,after two bytes of data have been read, a transmit buffer counter CNTTXand a receive buffer counter CNTRX both are reset to "0". Assuming thatthe leading address of a receive buffer is, for example, "RXBF0", theninput data is set in the buffer at "RXDF0+CNTRX" (S28), and then thereceive buffer counter CNTRX is incremented (S29). After the input ofthe information code, the number of data, and the data, whether or notthe received data is a reply to data written by a transmission from theown station is determined (S30). If the result of this decision ispositive, Y, whether or not the information code, the number of data andthe data are correct is determined (S31), and then the program ends.Such a procedure is executed with, among the contents shown in FIG. 21B,the write-in and read-out of all data, the write-in and read-out of anoptics control program, and the write-in and read-out of a program.

If the received data is not a reply as determined in the step S30,whether or not a continuous transfer is to occur is determined (S32). Ifthe answer of this step S32 is negative, the program advances to a stepS40, FIGS. 24A-24B, for setting the leading address TBJCD of aninformation code table in an information code table pointer. As shown inFIG. 46, the information code table is constituted by information codes,numbers of data, and addresses, where the data are stored. When thenumber of data is two or more, the leading address is stored.

In a step S41, whether or not the information code and the pointerthereof (PTJCD-PTJCD+10) are coincident is determined. If they are notcoincident, "15" is added to the pointer PTJCD (S42), and then whetheror not the information code and the pointer thereof (PTJCD-PTJCD+10) arecoincident is determined again (S41). This is repeated until theinformation code and the pointer thereof become coincident. When theyare coincident as determined in the step S41, the information code isset in transmit data buffers TXBF0 to TXBF10 (S43). Then, the contentsof the numbers of data PTJCD+11 and PTJCD+12 existing in the informationcode table are set in transmit data buffers TXBF11 and TXBF12,respectively (S44).

Subsequently, the numbers of data are converted to decimal numbers andthen set in a C register (S45). Thereafter, "0" is set in a B register(S46). Then, the content of the number of data PTJCD+13 is set in an Hregister while the content of the number of data PTJCD+14 is set in an Lregister (S47). Next, the C register is decremented (S48). Subsequently,in steps S49-S56, the read-out of data (S51 and S52), the write-in ofdata (S53 and S54), the decrement of the transit buffer counter CNTTXand B register (S55 and S56), and other processing are sequentiallyexecuted until a borrow occurs.

The read-out of data is executed when the received number of data is "0"as determined in the step S50. Specifically, the content of an addressindicated by the content of (HL+B) is set in an A register (S51), andthen the value of the A register is set in the transmit data bufferTSBF13+B (S52). The write-in of data is effected when the receivednumber of data is "1" as determined in the step S50. Specifically, thecontent of the receive buffer RXBF0+B is written to an address indicatedby the content of (HL+B) (S53) and then in the transmit buffer TXBF13+B(S54). When a borrow occurs in the C register in the step S49, "0" isset in the B register (S57), and then the receive buffer counter CNTRXis decremented (S58). The content of the transmit buffer TSBF0+B iscontinuously sent until a borrow occurs (S59 and S60). When a borrowoccurs in the receive buffer counter CNTRX, the processing ends.

Referring again to FIGS. 23A-23B, when a continuous transfer is to occuras determined in the step S32, whether or not the block "0" is receivedis determined (S32). Only if the block "0" is received, "0" is set in areceive block counter CNTBLK (S34), and then the leading address"TBxxx"+CNTBLK*64 of the data to continuously transfer in an HL register(S35). The leading address "TBxxx" is representative of the leadingaddress of, for example, a RAM 1003 or that of program addresses.Subsequently, the information code is set in the transmit buffers TXBF0to TSBF10 (S36). ASCII data "36(H)" and "34(H)" representative of thenumber of data "64" are set in the transmit data buffers TSBF11 andTXBF12, respectively (S37). Subsequently, "64" is set in the C register(S38) while "0" is set in the B register (S39). This is followed by thestep 48 and successive steps, FIGS. 24A-24B, to read, write and transmitdata. In the case of continuous transfer, the embodiment directlytransfers data without converting it to ASCII code.

The data of the copier 1 to be interchanged with the control device 141are ASCII data. Hence, when the operation time, for example, of thecopier 1 is 4.321 hours. "34H", "33H" "32H" and "31H" are stored in dataareas DONTM1, DONTM2, DONTM3, and DONTM4, respectively. Therefore, tocount the operation time of the copier 1, when one hour expires, anotherdata area DONTM is incremented, the data of this area DONTM is againconverted to ASCII data, and then the ASCII data is set in the areasCONTM1 to DONTM4. Such processing is also true with other data.

As stated above, regarding the communication between the control device141 and the copier 1, an information code of data and the number of data"0" are sent in the event of read-out while an information code of data,the number of data and data are sent in the event of write-in. However,this will not be referred to for simplicity hereinafter.

A reference will be made to FIGS. 25-35 for describing the usualoperation of the control device 14. As shown in FIG. 25, the controldevice 141 displays a menu picture shown in FIG. 26 on a display 163,FIG. 14. In this condition, the control device 141 allows a menu No tobe entered. A menu number "1" is representative of a menu forregistering users to be dealt with by the control device 141. With thismenu, it is possible to register the type, product number and so forthof the copier 1 before shipment. A file name is implemented as a name,e.g., USR.MEM. When the menu number is inputted (S62), the controldevice 141 opens a file USR.MEM (S63 and S64) and then displays thecontents of the file (S65), as shown in FIG. 27. In this condition, thecontrol device 141 allows a register number (S66), user's name (S67),telephone number (S68), type of machine (S69) and product number (S70)to be sequentially inputted, while displaying corresponding picturesshown in FIGS. 28-32.

Subsequently, the control device 141 stores the input data in a MEM file(S71) and then displays a picture of FIG. 33 inquiring whether or not toend the registration (Y/N) (S72). When "Y" is inputted, the controldevice 141 closes the file and ends the registration (S73 and S74) andreturns to the step S62. When "N" is inputted, the program returns tothe step S66 to display the picture of FIG. 28, thereby allowing anotheruser to be registered.

Assume that the USR.MEM file includes the type code and the productnumber of the copier 1 represented by characters "FT4060" and "1234567",respectively. Then, as shown in FIG. 27, there appears on the display163 "00001; A Copy Service; 37771234; FT4060; 123456". Here, "00001"heading the information is representative of the register number, thefollowing "A Copy Service" is representative of the user's name, and thesubsequent "37771234" is representative of a telephone number: asemicolon is used to divide nearby items.

Control data registration associated with the menu number "2" (S75-S81)and initial mode registration associated with the menu number "3"(S82-S89) will be described specifically later.

Referring to FIG. 39, control to be executed at the time of delivery ofthe copier 1 will be described. At the time of delivery, initial datatransmission data indicative of whether or not all the data associatedwith the copier 1 have been stored in the control device 141 is storedin a predetermined address DCSSDF of the nonvolatile RAM 102. "0" storedin the address DCSSDF shows that all the data have not been stored inthe control device 141 while "1" shows that all the data have beenstored. Specifically, when the copier 1 is installed at the user'sstation, it is connected to the control device 1 by the telephone line142 and CCU 144, as shown in FIG. 1. As the power switch of the copier 1is turned on, the CPU 100 of the copier 1 determines the content of theaddress DCSSDF (S91) and, if it is "0", sends the product number to thecontrol device 141 together with an installation alarm (S92). Theinstallation alarm is a signal which causes the copier 1 to start on analarm transmission. If the content of the address DCSDF is "1", the CPU100 ends the program.

How the control device 141 operates at the time of delivery of thecopier 1 will be described with reference to FIG. 40. As shown, onreceiving the installation alarm, the control device 141 reads theinitial data transmission data (S101 and S102) and then checks it(S103). If the data is "1", the control device 141 ends the processingwhile, if it is "0", the control device 141 executes a step S104 andsuccessive steps. Specifically, the control device 141 opens thepreviously stated file USR.MEM and then determines whether or not theuser matching the received type code and product number is registered(S104). If the answer of this step S104 is negative, the control device141 displays such a result (S105). In this case, an arrangement may bemade such that the program jumps to the user registration control stepsS63-S74, FIG. 25 (S106 and S107). If the user is registered asdetermined in the step S104, the control device 141 automaticallydetermines a file name on the basis of the user's name stored in thefile USR.MEM, generates a file of the file name, and then opens (S108).For example, assuming A Copy Service, the control device 141 generates afile "A Copy Service, DTF"; "DTF" is an expander of the file name andindicative of a data file generated at the time of delivery.

Subsequently, the control device 141 writes the current date in thefile, reads all the data relating to the values set in the copier 141(S109), and then stores the received information code and data in thefile (S110). On storing all the data (S111), the control device 141closes the file (S112), displays the file name together with an endmessage, e.g., "Filed installation data" (S113), and then writes "1" asthe initial data transmission data (S114).

The file "A Copy Service, DTF" generated by the above procedure may berepresented by characters "19920314; 51050080101/01/00;51010130101/01/00; . . . ". Here, "19920314" heading the file isindicative of the date, "51050080101" is an information code, "01" isthe number of data, and the "00" is the data. The information code, thenumber of data and the data are divided by "/" while the others aredivided by ":".

During the data up-loading at the time of installation, the embodimentcauses the control device 141 to read data set in the copier 1 inresponse to the installation alarm. Alternatively, the copier 1 may sendall the data thereof to the control device 141 after the installationalarm. Specifically, in such an alternative procedure, the copier 1sends the installation alarm and then the type code, product number, anddata group stored in a memory. On receiving the installation alarm, thecontrol device 141 searches for the user stored in the file USR.MEM andmatching the following type code and product number, automaticallygenerates a file, e.g., "A Copy Service. DTF", opens it, and thenexecutes the above-described control. Further, control data may beregistered at the control device 141.

Referring to FIGS. 34 and 35 as well as to FIG. 25, control dataregistration associated with the menu number "2", will be described.When the control data registration designated by the menu number "2" isselected, the control device 141 opens a file storing registered controldata (S75 and S76). At the instant, the file name is determined as"CONTROL D REGISTER, DAT" beforehand. The control device 141 requeststhe operator to enter an information code by use of a picture shown inFIG. 34. As the operator enters an information code (S77), the controldevice 141 stores it in the file (S78) and then inquires the operatorwhether or not to end the registration (Y/N) by use of a picture shownin FIG. 35 (S79). When "Y" is entered, the control device 141 ends theregistration and closes the file (S80 and S81). If "N" is entered, theprogram returns to the step S76 to show the picture of FIG. 34 again.

When only the data storing the file "CONTROL D REGISTER, DAT" should bemanaged, an information code storing the file may be simply sent to theend of the file at the time of installation, instead of calling all thedata set in the copier 1. Further, whether or not all the data of thecopier 1 are stored in the control device 141 may be determined by usinga memory built in the control device 141. This memory should preferablybe implemented by a nonvolatile memory, e.g., a floppy disk or a harddisk.

The operation of the control device 141 in the above condition will bedescribed with reference to FIG. 41. To begin with, in steps S121-S123,the control device 141 determines whether or not the initial deliverydata file storing the names of all the users is present in order tomonitor the statuses of all the users registered at the file USR.MEM.This is effected, for example, during the night of the data of delivery.For example, the control device 141 searches for the data file "A COPYSERVICE, DFT" associated with "A Copy Service" which is registered atthe file "USR.MEM" (S123). When the data file of interest is present,the control device 141 executes usual monitor processing (a copy counterand whether or not a state analogous to an error has occurred on theday) (S131). If such a file is absent, the control device 141 determinesthat the copier 1 has just been delivered, generates a file (S124),reads all the data of the copier 1 (S125), and then stores them in "ACOPY SERVICE, DFT" (S126). On storing all the data (S127), the controldevice 141 closes the file (S128) and then displays the file namegenerated in the step S129 together with an end message, e.g., "Storeddelivery data" (S128). Subsequently, the control device 141 executes theabove procedure with the next registered user (S130), returns to thestep S122, and ends this control on completing it with all theregistered users.

Again, only the data stored in "CONTROL D REGISTER. DAT" may beup-loaded. Why the control device 141 executes the above processingduring the night is that the copier 1 is used less frequency than duringthe day. The processing is automatically executed by the timepiecefunction of the control device 141. Alternatively, when the copier 1 hasa timepiece, the copier 1 may send an alarm to the control device 141 ona predetermined day. Further, when the alarm is to be sent, the copierID code which the CCU 144 adds may be used in place of the type code andproduct number to be sent by the copier 1. A printer 406. FIG. 14, isincorporated in the control device 141. Hence, the contents of the filemay be printed by the printer 165 to provide more easy-to-see data thanwith a display. In addition, this file may be loaded by a tablecalculation program so as to print an easy-to-see table, as shown inFIG. 45 specifically.

A reference will be made to FIGS. 36-37, as well as to FIG. 25, fordescribing control which allows the control device 141 to determine thetime of delivery and automatically down-load initial mode data to thecopier 1. The control device 141 usually displays the control menu shownin FIG. 26, as stated earlier. When the menu number "3" is selected, thecontrol device 141 displays a picture shown in FIG. 36 to inquire thename of the user whose initial modes are to be registered (S82 to S83).As the user's name is entered, the control device 141 searches for afile "USER'S NAME, DFT" (S84), opens it, and then inquires aninformation code by use of a picture shown in FIG. 37. This file isgiven with a particular name, e.g., "A COPY SERVICE, DFM"; the expanderis indicative of the registration file storing initial modes. If such afile is absent, the control device 141 generates it and opens it.Subsequently, as the information code indicative of the initial modedata, the number of data and data are entered (S85 and S86), the controldevice 141 inquires whether or not to end the initial modes (Y/N) by useof a picture shown in FIG. 38. If "Y" is entered, the control device 141ends the registration and closes the file (S88 and S89) while, if "N" isentered, it returns to the step S84 to display the picture of FIG. 37again.

The initial mode registration file stores an information codecorresponding to the mode selection data, the number of data, and datain sequence. The information code and the number of data are divided by"/" while the others are divided by ":". When the file "A COPY SERVICE,DFM" stores, for example, an initial mode for muting a buzzer and aninitial mode for decrementing the copy number display by 1 at a time, asdesired by the user, they are represented by characters"51050080101/01/01;51010130101/01/01; . . . ", by way of example.

At the time of delivery, the initial modes are set by a procedure whichwill be described with reference to FIG. 42. After the previouslydescribed data up-loading at the time of delivery, the control device141 searches for the file "A COPY SERVICE, DFM" (S141) and, if it ispresent, opens it (S142). If this file is absent, the control device 141displays a message and waits (S143). After opening the file, the controldevice 141 sequentially reads the contents of the file and sends them tothe copier 1 while deleting the division mark "/" (S145). On reading thedivision mark ":", the control device 141 does not send the data andwaits until a code identical with the information code sent has beenreturned (S146). If the code identical with the information code is notreceived, the control device 141 displays an error (S147) and then endsthis procedure.

The control device 141 executes the above processing up to the end ofthe file "A COPY SERVICE, DFM". As the file ends, the control device 141closes the file (S144 and S148), displays an end message (S149), andthen ends this processing. On receiving the data, the copier 1 rewritescorresponding initial mode data. For example, a mode data "1" for mutingthe buzzer and a decrement mode data meant for the copy counter arewritten to areas DMBZOF and DMCPCT, respectively. In this condition,when the power switch of the copier 1 is ON, the copier 1 references thearea DMBZOF and, if it is "1", mutes the buzzer thereof. Also, when thecopy start key is pressed, the copier 1 references the area DMCPCT and,if it is "1", displays the set number of copies on the copy numberdisplay and sequentially decrements it by 1 at a time.

Referring to FIGS. 43A and 43B, how data is down-loaded from the controldevice 141 to the copier 1 when the memory of the copier 1 is clearedwill be described. As shown in FIG. 43A, in a service mode check flowS150, the main switch of the copier 1 is turned on (S152) with the modeclear/preheat key 189 and program key 153 being pressed (S151 and S152),thereby setting up a service mode. In this mode, a service mode numberis entered on the numeral keys 156 (S153), and then the enter key 155 ispressed. Then, the copier executes particular service mode processingassociated with each of the service mode numbers. Assume that a memoryclear number "100" is set as a service mode number beforehand. Then,when the number "100" is entered and then the enter key 155 is pressed,a memory clear set mode flow S160 shown in FIG. 43B is executed. At thisinstant, memory clear processing occurs in response to the numeral "1"and enter key 155 while the program returns to the service number inputstate in response to the numeral "0" and enter key 155 (S161-S163). Inthe memory clear processing, the copier 1 rewrites the memory thereof byreferencing a default data table. As shown in FIG. 44, the default datatable is stored in the RAM 102 and made up of the addresses and initialvalues of data to rewrite: both the address and the data have one byte.

As shown in FIG. 43B, the copier 1 sets the leading address TBTFDT ofthe default data table in a memory clear pointer PTMCR (S164). In FIG.44, the content of the memory clear address pointer PTMCR is indicativeof the bias data address DBBIAS by way of example. The copier 1 writesbias data (content of PTMCR+2) "80H" in the address indicated by thecontent of the pointer PTMCR (S165) and then adds "3" to the content ofthe pointer PTMCR (S166). The copier 1 repeats these steps until thecontent of the pointer PTMCR becomes equal to the address TBDFED andthen ends the memory clear processing (S167). Finally, the copier 1sends a memory clear alarm, type code and product number to the controldevice 141.

On receiving the memory clear alarm, the control device 141 opens theuser registration data file "USR.MEM" to search for the user on thebasis of the type code and product number. Then, the control device 141searches for the data file generated at the time of installation, e.g.,"A COPY SERVICE, DFT". If this file is not available, the control device141 displays a suitable message, e.g., "A COPY SERVICE DFT notavailable", energizes a buzzer several times, and waits. If such a fileis available, the control device 141 opens it, sequentially reads thecontents, and sends them to the copier 1. This procedure is executedwhen the main which switch is ON in the same manner as when the controldevice 141 sets initial modes.

This embodiment down-loads data from the control device 141 to thecopier 1 when the memory of the copier is cleared and, therefore,achieves the following advantages. Some modern copiers 1 switch thepower source of the RAM 102 from a main power source to, for example, alithium battery when the power source is turned off, so that data storedin the RAM 102 may not be lost. In this type of copier 1, when thecontrol board has failed, it is bodily replaced with another in order tosimplify repair and reduce maintenance cost. However, if the data storedin the RAM 102 which is mounted on the control board is not transferredto a new control board, it is necessary to set various modes of thecopier 1 all over again and readjust the image quality. By contrast,when the control board is replaced, the embodiment executes the memoryclear processing for setting image forming data and initial modes indefault values in the service mode. As a result, data generated at thetime of delivery of the copier 1 are automatically down-loaded toeliminate troublesome operations including the above-mentioned moderesetting and image quality readjustment.

Further, since the embodiment monitors the copier 1 during the night byup-loading the data of the copier 1, the latest data can be down-loadedin the event of replacement of the control board. Control for effectingthis will not be described specifically since all that is required is toreplace the data file of the copier generated at the time of deliveryand to be down-loaded at the time of memory clearing with the latestdata.

In addition, the control device 141 can be implemented by a personalcomputer, a work station or particular equipment developed to controlthe copier 1. Therefore, there can be executed processing which would betoo heavy to be executed by the copier 1 alone.

Referring to FIG. 47, an alternative embodiment of the present inventionwill be described. In this embodiment, the same or similar constituentsas or to those of the previous embodiment are designated by likereference numerals, and a detailed description will not be made to avoidredundancy. With this embodiment, it is possible to calculate, forexample, image forming condition data up-loaded from the copier 1 to thecontrol device 141 by neuro-fuzzy control and AI (ArtificialIntelligence) control and then down-load the results to the copier 1 orto effect fault diagnosis with the copier 1. Further, when the copier 1is a digital copier of which photoelectrically transduces a documentimage and processes the resulting digital signal, it is possible to up-or down-load image data so as to edit and manipulate an image, translatea document or offer an image service.

A facsimile terminal 146, a printer 147, a key card 148, a coil rack 149and a personal computer 150 may be connected to the CCU 144 in additionto the copier 1. When part or all of the programs owned by the controldevice 141 are loaded in the personal computer 150, the serviceman cansupervise the copier at the user's side by carrying the personalcomputer 150. While the embodiment allows the control device 141 andcopier 1 to interchange data via the CCU 144 and exchange 143, thefunctions of the CCU 144 and exchange 143 may be incorporated in thecontrol device 141 and copier 1. Further, the control device 141 andcopier 1 may be connected by a cable in place of the telephone line 142or communicate with each other by radio or light.

A reference will be made to FIGS. 48-50 for describing other functionsavailable with the present invention.

The CPU 100 of the copier 1 shown in FIGS. 1 and 12 executes a main flowshown in FIG. 48 after the power switch of the copier 1 has been turnedon. Specifically, the CPU 100 executes initialization and thenprocessing in a usual mode. Apart of this flow, the CPU 100 communicateswith the control device 141 by interrupt processing every time acommunication request and an auto-call request is generated, althoughnot shown in the figures.

In the usual mode, the CPU 100 executes image formation and variouskinds of automatic adjustment depending on conditions. The followingdescription will concentration on automatic VL adjustment by way ofexample. The automatic VL adjustment refers to the automatic adjustmentof the lamp voltage for reducing, for example, the contamination of thebackground ascribable to the fall of the sensitivity of thephotoconductive drum 35 due to aging, change in the sensitivity of thedrum 35 due to low temperature, contamination of the optics, decrease inthe quantity of light due to the deterioration of the lamp, etc. Inpractice, when the power source is turned on, the CPU 100 executes aspecific automatic VL adjustment shown shown in FIG. 50 by calling itfrom the main routine. Specifically, assume that correction using theresidual voltage VR is to be performed with the temperature is low.Then, when the temperature of the drum 35 is higher than 25 degrees orwhen a predetermined number of copies have been produced, the potentialsensor 39, FIGS. 2 and 8, senses the residual potential VR of the drum35. In response to the output of the sensor 39, the CPU 100 determineswhether or not a copying operation has ended. If a copying operation hasended, the CPU 100 starts on VL detection. For VL detection, the CPU 100causes the first scanner 24 to move to below the VL pattern 124, FIG. 3.The resulting reflection from the VL pattern 124 is focused onto thedrum 35 having been uniformly charged by the main charger 37, therebyforming a VL pattern on the drum 35. The potential sensor 39 senses thesurface potential (white area potential VL) of the VL pattern andcorrects the voltage to the lamp 22 on the basis of the ratio of thepotential VL to a reference lamp voltage.

FIG. 49 shows part of the processing in the usual mode which relates tothe communication of the copier 1 with the control device 141. When thecontrol device 141 generates a communication request, the CPU 100determines whether or not automatic adjustment, including theabove-stated automatic VL adjustment, is under way. If the adjustment isunder way, the CPU 100 continues the adjustment while inhibiting thecommunication. If the adjustment is not under way, the CPU 100 executesa communication with the control device 141 and then returns. If imageformation is in progress when the transmission request is generated, theCPU 100 also continues the image formation while inhibitingcommunication.

Another function available with the present invention will be describedhereinafter. Since the function to be described can be implemented bythe same hardware as the previous embodiments, the hardware will not beshown or described. The communication between the control device 141 andthe copier 1 should preferably be held in the time zone in which thetelephone line 142 is not frequently occupied. For this purpose, thehuman body sensor 114, FIG. 12, is provided on the front end of thecopier 1 and plays the role of deciding means. This will be describedwith reference to FIG. 51.

As shown in FIG. 51, the CPU 100 of the copier 1 determines whether ornot the sensor 114 has turned on and, if it has not turned on, resets ahuman body sense flag to "0" and then returns. When the sensor 114 hasturned on, the CPU 100 increments a human body counter ON₋₋ COUNT by 1.Then, the CPU 100 determines whether or not the count of the counterON₋₋ COUNT has exceeded a predetermined value ("100" in the figure). Ifthe count is short of the predetermined value, the CPU 100 returns: ifotherwise, it sets the human body sense flag to "1", clears the counterON-COUNT to "0", and the returns. By so sensing a human body withreference to the flag, it is possible to prevent persons simply walkingpast the copier 1 from being sensed.

FIG. 52 demonstrates a procedure relating to the communication of thecopier 1 with the control device 141 and to be executed by the CPU 100in this embodiment. As shown, when the control device 141 generates acommunication request, the CPU 100 determines whether or not the humanbody sense flag is "1" and, if it is not "1", sets up a communicationwith the control device 14 and then returns. If the flag is "1", the CPU100 determines that a person to use the copier 1 is present and returnsimmediately by inhibiting the communication.

FIG. 53 shows another communication procedure to be executed by the CPU100 of the copier 1. When a communication with the control device 1 isunder way, the CPU 100 determines whether or not the human body senseflag is "1" and, if it is not "1", returns immediately. If the flag is"1", the CPU 100 interrupts the communication and then returns.

FIG. 54 shows still another communication procedure to be executed bythe CPU 100. When a communication with the control device 1 is underway, the CPU 100 determines whether or not the human body sense flag is"1" and, if it is not "1", returns immediately. If the flag is "1", theCPU 100 determines whether or not the communication under way is torewrite data representative of adjusted image forming conditions. If theresult of this decision is negative, the CPU 100 interrupts thecommunication and then returns: if otherwise, it returns immediately,awaits the end of the communication, and then sets up the usual imageforming mode since the interruption might destroy data existing in thecopier 1.

Assume that the human body sensor 114 turns on while a communication isheld between the copier 1 and the control device 141, setting the humanbody sense flag to "1". Then, the CPU 100 should preferably inform theperson standing by the copier 1 of the communication under way on theoperation board 70. For example, as shown in FIG. 55, the CPU 100 causesthe magnification section (D12) of the pattern display 72, FIG. 11, todisplay "CSS" and turn on a message "WAIT". When the communication withthe control device 141 ends, the CPU 100 causes the display 72 to turnoff these indications.

If desired, the human body sensor 114 may be replaced with an objectsensor capable of sensing even objects other than human bodies by, forexample, infrared rays.

FIG. 56 demonstrates another function available with the presentinvention and relating to the communication of the copier 1 with thecontrol device 141. As shown, when the control device 141 sends acommunication request to the copier 1, the CPU 100 of the copier 1determines whether or not a program mode is set up. The program moderefers to a mode which allows the operator to register a combination ofdesired image forming modes (enlargement, reduction, two-sided printing,etc.) by use of the program key 80, FIG. 10, provided on the operationpanel 70. If the program mode is not set up, the CPU 100 causes thecopier 1 to hold a communication with the control device 141 and thenreturns. If the program mode is set up, the CPU 100 returns after themode has ended. Specifically, when the control device 141 generates acommunication request while the program mode is under way, the CPU 100gives priority to the program mode and inhibits the copier fromcommunicating with the control device 141.

FIG. 57 shows another processing of the CPU 100 relating to thecommunication of the copier 1 with the control device 141. As shown, theCPU 100 determines whether or not a program mode registration request isgenerated while the copier 1 is communicating with the second device141. If the result of this decision is negative, the CPU 100 returns. Onthe generation of the request, the CPU 100 interrupts the communicationwith the control device 141 and then returns.

FIG. 58 shows another alternative embodiment of the control system inaccordance with the present invention. In this embodiment, a controldevice 16 is located at a service station and connected to the copiers(PPCs) or similar image forming apparatuses 1 located at the users'stations by a switched telephone network 17. At each user's station, aCCU 18 is installed for controlling the communication of the copier 1with the control device 16. The copier 1 is connected to the CCU 18. Atelephone set 19 and a facsimile apparatus 20 are also connectable tothe CCU 18.

While a plurality of copiers 1 are shown as being connected to each CCU18, they may, of course, be replaced with a single copier 1. The copiers1 may each be of a different type and may be replaced with printers orother image forming apparatuses. Let the maximum number of copiers 1connectable to each CCU 18 be five by way of example. The CCU 18 andassociated copiers 1 are connected by a multidrop system of RS-485standard. The communication between the CCU 18 and each copier 1 iscontrolled by a basic data transmission control procedure. The CCU 18 iscapable of communicating with any one of the associated copiers 1 bysetting up a data link by a centralized control polling/selecting systemin which it plays the role of a control station. Each copier 1 isprovided with an address set switch for setting a value particularthereto, and the polling address and selecting address of the copier 1are determined on the basis of the set value.

FIG. 59 shows a specific construction of the CCU 18. The CCU 18corresponds to the CCU 144 included in the control system of FIG. 1.When a communication from the switched telephone network is meant forthe telephone 19 (or the facsimile apparatus 20), the CCU 18 connectsthe telephone network, to the telephone 19 (or the facsimile apparatus20). When the communication is from the control device 16, the CCU 18connects the telephone network to a modem 28). The CCU 18 iscommunicable with the copier 1 via a communication interface (IF) 283which is implemented as an RS-485 transceiver. Such control andprocessing are executed mainly by a CPU 284 according to controlprograms stored in a ROM 285. A RAM 286 stores interim results ofprocessing and temporarily stores a communication text. Also, variousparameters necessary for the operation of the CCU 18 are written to theRAM 286 from the control device 16. Usually, the CCU 18 is continuouslypowered throughout the day to be communicable with the control device 16anytime. At the same time, the RAM 286 is backed up by a battery 287 inorder to prevent the above-mentioned parameters from being lost due tothe accidental shut-off of the power source or similar cause. Atimepiece 288 and an automatic total counter call permit switch 289whose function will be described later are also built in the CCU 18.

FIG. 60 shows a specific construction of the control device 16 includedin the system of FIG. 58. As shown, the control device 16 is generallyconstructed in the same manner as the control device 141 shown in FIG.14. Specifically, the control device 16 has a host computer 161, amagnetic disk or similar external storage 162 for storing supervisorydata and other data (corresponding to the memory shown in FIG. 14), adisplay 163, a keyboard 164 playing the role of operating means, aprinter 165 for outputting supervisory data, and a modem 167 connectableto the telephone network 17.

FIG. 61 shows control circuitry incorporated in each copier 1 of FIG.58. The mechanical arrangement of the copier 1 is essentially the sameas the arrangement described with reference to FIG. 2 and other figures.Also, the control circuitry of FIG. 61 is generally similar to thecircuitry of FIG. 12. Hence, the same blocks as the blocks of FIG. 12are designated by like reference numerals and will not be describedspecifically. In the circuitry of FIG. 61, a communication IF unit 103communicates with the CCU 18. An address set switch 115 allows anaddress particular to the copier 1 to be selected out of 1 to 6. Acommunication permit switch 116 is operable to selectively permit orinhibit the communication of the copier 1 with the CCU 18.

The operation of this embodiment will be described in detail withreference mainly to FIG. 62A and successive figures. To begin with, aremote informing function will be described with reference to FIGS.62A-62C and FIG. 58. As shown, when the remote inform key 83, FIG. 10,provided on the operation panel 70 of the copier 1 is pressed, remoteinformation data is sent from the copier 1 to the CCU 18. On receivingthis data, the CCU 18 calls the control device 16 by use of a telephonenumber set therein beforehand and then sends the data to the controldevice 16. Usually, the control device 16 is located at a servicestation. Here, the CCU 18 is assumed to send, among a plurality of kindsof data sent from the copier 1, only data of the kind set in the CCU 18beforehand to the control device 16. Data of this kind is set in the CCU18 by the control device 18 via the telephone network 17.

As the CCU 18 fully sends the predetermined data to the control device16, it sends the result of communication with the control device 16 tothe copier 1 of interest. The copier 1, therefore, can see if thecommunication was successful or if it was unsuccessful due to someerror. It is a common practice to provide a copier with a self-diagnosisfunction. With this function, a copier informs the operator or theserviceman of a dangerous condition or a disabled condition thereof,e.g., when the fixing temperature is abnormal or when the adjustment ofa certain adjustable portion using an electronic volume fails. Thisinformation is brought to the operator or the serviceman as "ERROR" or"SERVICEMAN CALL".

As shown in FIG. 62B, when an error is found by the self-diagnosis ofthe copier 1, the copier 1 also sends remote information data resultedfrom the diagnosis to the CCU 18. Then, the CCU 18 sends the data to thecontrol device 16 and, on completing the communication, sends the resultof communication to the copier 1.

Further, assume that the copier 1 determines that maintenance ispreferable, e.g., when the current condition is quite close to an error,if not an error, by self-diagnosis. Then, as shown in FIG. 62C, thecopier 1 sends remote information data for precaution. While the copier1, of course, cannot be used in the event of an error found byself-diagnosis, it is left usable in the event of a precaution and canproduce a copy when a document is set and the start key is presseddespite the communication under way. At this instant, the communicationmay be interrupted if the copying operation increases the load on thecontroller of the copier 1 or if it is apt to disturb the data beingsent. Since the remote information data for precaution is not urgent, itis preferable that the CCU 18 received the data does not send it to thecontrol device 16 immediately, i.e., sends it at a time convenient for acommunication. For example, this communication may be held in the timezone in which the telephone 19 and facsimile apparatus 20 connected tothe CCU 18 are not frequently used or the time zone in which the trafficof the telephone network 17 is not heavy. Such a time is set in the CCU18 by the control device 16, and the copier 1 can see the time bycomparing it with the timepiece 288, FIG. 59. In the case of such aprecaution, the CCU 18 does not send the result of communication to thecopier 1.

How the control device 16 accesses the copier 1 will be described withreference to FIGS. 63A-63C. Generally, the control device 16 accessesthe copier 1 for three different purposes, i.e., for sending a readrequest (FIG. 63A), for sending a write request (FIG. 63B), and forsending an execute request (FIG. 63C). The read request is to readlogging data, various set values and sensor outputs out of the copier 1.The write request is to send various values to set and other data to thecopier 1 for rewriting existing data. The execute request is to causethe copier 1 to execute, among others, a testing procedure. In any oneof the procedures shown in FIGS. 63A-63C, the control device 16 dialsthe CCU 18 to which the copier 1 of interest is connected and then sendsthe request. On receiving the request, the CCU 18 sends request data tothe copier 1 for which the request is meant. In response, the copier 1processes the content of the request and then sends a correspondinganswer to the CCU 18. The CCU 18 sends the answer to the control device16 and ends a single unit of processing.

FIGS. 64A-64C show procedures for the control device 1 to access the CCU18. Again to access the CCU 18, the control device 16 uses a readrequest (FIG. 64A). a write request (FIG. 64B) or an execute request(FIG. 64C). The read request is to read set parameters and statuses outof the CCU 18 and to read information associated with the copier 1 andwhich the CCU 18 may have read and stored therein beforehand. The writerequest is to set parameters of the CCD 18 by sending data from thecontrol device 16. The execute request is to cause the CCU 18 to testitself, e.g., to check the functions of its own.

FIG. 65 shows a procedure in which the CCU 18 accesses the copier 1without using the control device 16. As shown, the CCU 18 accesses thecopier 1 to read information representative of the inside conditions ofthe copier 1 and store them in the CCU 18 so as to allow the controldevice 16 to read them afterwards. Generally, a copier is provided with,for example, a total copy counter for a maintenance purpose. The copier1 periodically sends the content of the total copy counter to the CCU18. Then, the control device 16 can see the total number of copies evenwhen the copier 1 is unable to communicate, e.g., when the power sourceof the copier 1 is turned off. This can be done since the CCU 18 has afunction of reading the inside information of the copier 1 and storingthem in itself, as stated earlier. When, among the parameters set in theCCU 18, the time for collecting the value of the total copy counter isreached as indicated by the timepiece 288. FIG. 59, built in the CCU 18,the CCU 18 sequentially requests all the copiers 1 connected thereto tosend total copy numbers and performs this every day. The CCU 18 storesthe new total copy numbers from the copiers 1 in the RAM 2, FIG. 59, andupdates them every day. When the copier expected to send the total copynumber to the CCU 18 is unable to communicate due to, for example, theturn-off of the power source, the CCU 18 skips it and executes theprocessing with the next copier 12. After sending the request to all thecopier 1, the CCU 18 again sends the request to the copier 1 which isskipped. Usually, the time for collecting the total counter values isset at the nighttime during which the power sources of the copiers 1 areexpected to be turned off. Then, as the power sources of the copiers 1are turned on as the time elapses, the communication is held while thecopiers are idling just after the turn-on of their power source or whenthey are adjusted.

Two different approaches are available to transfer the total copynumbers from the RAM 286 of the CCU 18 to the control device 16. One isto cause the control device 16 to periodically access the CCU 18, e.g.,on a monthly add-up day. The other is to cause the CCU 18 toautomatically send the total copy numbers to the control device 16 onthe data for automatically calling the total counter values and set inthe CCU 18 beforehand. To select one of these methods, the automatictotal counter call permit switch 289, FIG. 59, of the CCU 18 isoperated. When the switch 289 is in an ON state, the CCU 18 calls thecontrol device 16 by use of a telephone number indicated by theparameter set in the CCU 18 and then sends the counts. When the switch289 is in an OFF state, the CCU 18 waits for the access from the controldevice 16. It is to be noted that data other than the total copy numbermay be periodically sent to the control device 16 in place of or inaddition to the total copy number.

FIG. 66 lists parameters to be set in the CCU 18. As shown, the typecode and serial number are registered for each copier 1 to which aparticular address is assigned. The type code and serial number are sentto the control device 16 in the event of report from the copier 1 orused to determine the address of the copier 1 to select in the event ofaccess from the control device 16. Also, the telephone number of thedestination, the number of times and interval of redialling and thekinds of data to send to the control device 16 are set for each cause ofremote information. Regarding remote information for precaution, thetime for reporting the control device 16 is also set. A check sum isadded to each block of the parameters so as to detect an occurrence thatthe parameters are accidentally changed or lost due to the malfunctionof the CCU 18 or the consumption of the back-up battery 187. Theseparameters are written to the CCU 18 by the control device 16 via thetelephone network 17. Alternatively, a portable device for setting theparameters may be directly connected to the CCU 18, or exclusiveoperating means may be provided on the CCU 18.

FIGS. 67A-67C each shows a specific format of data to be sent at thetime of remote information. FIG. 67A shows the format of data to be sentfrom the copier 1 to the CCU 18. As shown, the field heading the formatis indicative of the cause of remote information, i.e., the depressionof the remote inform key, the error found by self-diagnosis, or theprecaution. This field is followed by the inside conditions of thecopier 1 including conditions of tone, oil, sheets and otherexpendables, outputs of various sensors, set values of adjustablesections, and connection of units.

FIG. 67B shows the format of data to be sent from the CCU 18 to thecontrol device 16. As shown, a type number field and a serial numberfield are added to the head of data from the copier 1 to indicate thecopier 1 which generated the data. Also, the time when the cause ofinformation occurred is added to the tail of the data on the basis ofthe timepiece 288 of the CCU 18. Regarding the data field, the kink ofdata to send to the control device 16 depends on the parameters set inthe CCU 18. In this case, it is assumed that parameters are set in theCCU 18 such that only the number of times that an error is found byself-diagnosis and the conditions of the copier 1 are sent to thecontrol device 16.

FIG. 67C shows the format of data which the CCU 18 sends to the copier 1on completing the report to the control device 16.

FIG. 68 shows a format of data with which the control device 16 accessesthe copier 1 in the event of reading. As shown, the control device 16sends a request code representative of reading and a code representativeof an item to read to the CCU 18 after the type number and serial numberof the copier 1 of interest. In response, the CCU 18 removes the typenumber field and serial number field from the received data and sendsonly the read request code and item code to the copier 1. Then, thecopier 1 sends a read answer code, the received item code and thenrequested data to the CCU 18. Finally, the CCU 18 again adds the typenumber and serial number to the data from the copier 1 and then sendsthem to the control device 16.

FIG. 69 shows a format of data for the control device 16 to access thecopier 1 in the event of writing. In this case, the control device 16adds data to write to the item code. On the other hand, the CCU 18 sendsthe data actually written to the copier 1 after the item code field.While the data received by the copier 1 and the data sent from thecopier 1 are usually identical, they will differ from each other when,for example, the received data does not lie in a valid range and is,therefore, replaced with a boundary value.

FIG. 70 shows a format of data used in the event of execute processing.In this case, when the item code cannot designate an object to operatealone, the control device 16 sends a code representative of asupplementary content after the item code. On executing the requestedoperation, the copier 1 sends the result data to the control device 16.

FIGS. 71A-71C show respectively a format of data to be sent from thecontrol device 16 to the CCU 18 in the event of reading, a format ofdata to be sent in the event of writing, and a format of data to be sentin the event of execution. These data formats are substantiallyidentical with the data formats used to access the copier 1 except thatthe type number and serial number are replaced with a code designatingthe CCU 18.

FIG. 72 shows a format of data with which the CCU 18 accesses thecopier 1. The format is identical with the format used for the controldevice 16 to access the copier 1 as shown in FIGS. 68-70. The copier 1does not have to distinguish the accesses from the control device 16.

FIG. 73 demonstrates a main routine to be executed by the CPU 100 of thecopier 1, FIG. 61, for information control. As shown, assume that thecommunication permit switch 116 located at the outside of the operationpanel 70 of the copier is in an ON state. Then, when the remote informkey 83 of the operation panel 70, FIG. 10, is pressed, when an error isfound by self-diagnosis, or when a precaution is necessary, the CPU 100executes corresponding remote information processing.

FIG. 74 is representative of a subroutine included in the main routineof FIG. 73 and executed when the remote inform key 83 is pressed. Asshown, when the key 83 is pressed, the CPU 100 sends remote informationdata to the CCU 18. When the information is defective, e.g., when theCCU 19 does not answer the remote information, the CUP 100 causes theremote communication error indicator D8. FIG. 11, to glow or flash toinform the operator of the error. When the data is successfully sent tothe CCU 18, the CPU 100 resets an exclusive timer and then awaits theresult of communication from the CCU 18. The timer is assumed to count 3minutes. When the result of communication does not arrive at the copier1 within 3 minutes, the CPU 100 again causes the indicator D8 to glow orflash to inform the operator of the error. When the result ofcommunication arrives within 3 minutes, the CPU 100 checks it to see ifthe communication was successful and, if it was successful, displays theend of automatic communication, although not shown in the figure. If thecommunication failed, the CPU 100 again causes the indicator D8 to glowor flash and then returns to the main routine of FIG. 73.

FIG. 75 demonstrates a subroutine also included in the main routine ofFIG. 73 and relating to an error found by self-diagnosis. Thissubroutine is identical with the subroutine of FIG. 74 associated withthe remote inform key 83 except that data representative of the error issent to the CCU 18, and that the timer counts 20 minutes.

FIG. 76 shows a subroutine also included in the main routine of FIG. 73and relating to the remote information for precaution. In thissubroutine, remote information data for precaution is sent to the CCU18.

FIG. 77 shows a main routine which the CPU 100 executes when the CCU 18accesses the copier 1. Assume that data is received by the communicationIF unit 103 when the communication permit switch 116. FIG. 61, is in anON state. Then, the CPU 100 identifies a read request, a write requestor an execute request by referencing the head field and then executes acorresponding procedure. When the CPU 100 cannot identify any one of thethree different request, it returns an error code and then ends theprocessing.

FIG. 78 shows the read processing of FIG. 77 in detail. As shown, if theitem code received by the copier 1 is correct and readable, the CPU 100returns requested data; if otherwise, it returns an error code.

FIG. 79 shows the write processing of FIG. 77 in detail. As shown, ifthe received item code is not correct or readable, the CPU 100 returnsan error code. If the received item code is correct, the CPU 100 checksthe value to write and, if it lies in a valid range, directly writes thevalue of the received data. If the value does not lie in the valid rangeand if it can be replaced with a boundary value, the CPU 100 writes theboundary value; if otherwise, the CPU 100 sends an error code and thenreturns. Whether or not the value can be replaced with the boundaryvalue is determined beforehand on an item code basis. Specifically, thefixing temperature and other values which would critically influencewhen rewritten despite that they lie in the valid range and thetelephone number of the service station and other values whose sizes aremeaningless are inhibited from being rewritten. On the other hand, theauto-reset time and other items having no influence on image quality areallowed to be replaced with the boundary value for convenience. Forexample, when it is desired to increase the auto-reset time as far aspossible, the copier 1 will automatically select the maximum value onlyif the maximum allowable auto-reset time is entered.

FIG. 80 shows the execute processing of FIG. 77 in detail. As shown, ifthe received item code is not correct or readable, the readable, the CPU100 determines whether or not the item needs a supplementary contentand, if the former does not need the latter, executes the designatedprocedure and then returns the result of operation. If the item ofinterest needs a supplementary content, the CPU 100 executes a procedurebased on the supplementary content. However, if the supplementarycontent does not lie in the valid range, the CPU 100 sends an error codeand then returns.

Hereinafter will be described the communication procedure between theCCU 18 and the copier 1.

FIG. 81 demonstrates a communication sequence to occur in an idle state,on assumption that five copiers 1 are connected to the CCU 18. As shown,the CCU 18 executes a polling cycle for sequentially sending a pollingsequence by of the polling address of each copier 1. When polled by thepolling address assigned thereto, the copier 1 sends a negative answerto the CCU 18 if a text to send is absent. The CCU 18 repeats thispolling cycle under the usual condition which does not need any othercommunication processing.

FIG. 82 shows a communication sequence to occur when a text to send ispresent in the copier 1 designated by the address 2. As shown, afterpolled by the assigned address, the copier 1 sends the text to theRS-485 line. FIG. 83 shows a specific sequence in which the CCU 18 sendsa text indicative of the result of communication to the copier 1designated by the address 5. As shown, after completing the currentpolling, the CCU 18 sends a selecting sequence and then a text to thecopier 1 of interest. Thereafter, the CCU 18 returns to the pollingcycle.

Processing of this embodiment which is directly pertinent to the presentinvention will be described hereinafter.

FIG. 84 demonstrates a procedure in which the CPU 100 of the copier 1selects an optimal communication mode on the basis of the connectioncondition (communicable or uncommunicable) and the ON/OFF state of thecommunication permit switch 116. FIG. 85 shows a subroutine included inFIG. 84 and associated with the connection condition while FIG. 86 showsa subroutine also included in FIG. 84 and relating to the state of theswitch 116.

To begin with, a reference will be made to FIG. 85 for describing thesubroutine for determining the connection condition of the copier 1 andCCU 18. It should be noted that the words "connection condition" refernot only to whether or not the line is connected but also to whether ornot communication control has been set up and whether or not, even whenthe line is connected, an error has occurred in the CCU 18. Hence,connection (communicable or uncommunicable) detecting means isimplemented by the CPU 100, the program stored in the ROM 101, and soforth. The detecting means determines whether or not the line isconnected and, if it is connected, determines whether or notcommunication control is set up on the basis of the presence/absence ofthe polling signal from the CCU 18.

As shown in FIG. 85, the CPU 100 determines whether or not the powersource has just been switched from an OFF state to an ON state (step20). If the answer of this decision is positive, Y, the CPU 100 clears atimer t which defines an interval between successive activations of theconnection detecting means to "0" (step 21). At the same time, the CPU100 resets a check flag flg-check for validating or invalidating theconnection detecting means "0". Subsequently, the CPU activates theconnection detecting means to determine whether or not the copier 1 isconnected to (communicable with) the CCU 18 (step 22). On determiningthat the former is connected to the latter (Y, step 23), the CPU 100sets a communication permit flag flg-comm to "1" (step 24); if otherwise(N, step 23), the CPU 100 resets the flag flg-comm to "0" (step 25).

When the power source is turned on as determined in the step 20, theconnection detecting means is activated without exception in the steps22-25. Why this is effected is that the CPU 100 can follow even a changein the connection condition when the power source of the copier 1 is inan OFF state, recognizing the latest connection information withaccuracy.

On the other hand, when the power source is not switched from an OFFstate to an ON state as determined in the step 20, the CPU 100determines whether or not the check flag flg-check is set or "1" (step26). The set/reset state of this flag will be described in relation tothe flowchart of FIG. 84. If the flag flg-check is reset or "0", the CPU100 returns immediately; if it is "1", meaning that the connectiondetecting means is valid, the CPU 100 executes a step 27 and successivesteps. In the step 27, the CPU 100 determines whether or not thecommunication permit flag flg-comm is set in the step 24 or 25 is "1" tosee if the communication between the copier 1 and the CCU 18 is allowed.If the flag flg-comm is "1", the CPU 100 again actives the connectiondetecting means (step 22) to determine whether or not the copier 1 andCCU 18 are connected. As a result, the condition detecting means ismaintained constantly valid and can continuously monitor the connectioncondition of the copier 1 and CCU 18. The CPU 100, therefore, can see achange from a connected state to a disconnected state by real timedetection and execute processing matching the condition immediately andaccurately.

On the other hand, when the flag flg-comm is not "1" as determined inthe step 27, the CPU 100 determines whether or not the timer t hasreached a predetermined time tmax (step 28) even though it does not haveto activate the connection detection means. If the answer of the stepS28 is positive, the CPU 100 clears the timer t to "0" and then advancesto the step S22; if otherwise, the CPU 100 increments the timer t by 1and then returns. Specifically, every time the CPU 100 starts on thisroutine, it increments the timer t by 1, clears the timer t when itreaches the predetermined time tmax to "0", and then activates theconnection detecting means in the step S22 to see if the copier 1 andCCU 18 are connected.

As stated above, even when the copier 1 and CCU 18 are not connected,i.e., when communication is allowed, the CPU 100 does not practicallyneglect the communication control mode, but it determines whether or notthe copier 1 and CCU 18 are connected every predetermined period of timetmax. Hence, when the CCU 18 is recovered from a fault, for example, andconnected to the copier 1, the recovery is detected immediately so as tovalidate the communication state.

Referring to FIG. 61, a procedure for the CPU 100 of the copier 1 todetermine a communication mode will be described. To begin with, thecommunication permit switch 116 shown in the figure will be described.The switch 116 is provided on the copier 1 to selectively permit orinhibit the communication of the copier 1 with the CCU 18. The switch116 may be implemented by a soft switch provided on a display, notshown, and responsive to a touch or a dip switch or similar hard switch.

Four different communication modes (1)-(4) which will be described areavailable with the illustrative embodiment, depending on the ON/OFFstate of the switch 116 and the connection condition of the CCU 18.

(1) When the switch 116 is OFF and the copier 1 is communicable with theCCU 18 (flg-comm=1), the communication between the copier 1 and the CCU18 is invalidated or validated and made busy. The connection detectingmeans is continuously invalidated (flg-check=0). In this condition,despite that the copier 1 and CCU 18 are connected (communicable), thecommunication can be selectively validated or invalidated by the switch116. It follows that when, for example, a serviceman received aserviceman call comes to the user's station for repair and performs areproduction test of, for example, a serviceman call, a serviceman callsignal or similar needless data is prevented from being sent.

(2) When the switch 116 is OFF and the copier 1 is not communicable withthe CCU 18 (flg-comm=0), the communication between the copier 1 and theCCU 18 is inhibited to inhibit the communication mode processing. Theconnection detecting means is continuously invalidated (flg-check=0). Inthis condition, when the communication mode function itself is notnecessary, e.g., when equipment with a communicating function is notinstalled, the CPU 100 is free from an extra load which would otherwisebe posed by the communication mode processing and lower the efficiency.

(3) When the switch 116 is ON and the copier 1 is communicable with theCCU 18 (flg-comm=1), the communication between the copier 1 and the CCU18 is validated to execute the communication mode processing. Theconnection detection means is maintained valid at all times(flg-check=1). As a result, a change in the connection condition(whether or not a communication can be held) of the copier 1 and CCU 18,particularly a change from the connected (communicable) state to thedisconnected (uncommunicable) state can be found by real-time detection.

(4) When the switch 116 is ON and the copier 1 is not communicable withthe CCU 18 (flg-comm=0), the communication between the copier 1 and theCCU 18 is inhibited to inhibit the communication mode processing. Theconnection detecting means is maintained valid at all times(flg-check=1). As a result, a change in the connection condition of thecopier 1 and the CCU 18, particularly a change from the disconnectedstate after the turn-on of the power source to the connected state(communicable state derived from the connection of the line, turn-on ofthe power source, recovery from a fault, etc.), can be found byreal-time detection. In addition, since the communication between thecopier 1 and the CCU 18 is inhibited, the communication mode isinvalidated to prevent the mode program for communication installed inthe copier 1 from being executed alone. This is successful in reducingthe load on the CPU 100 and promoting the efficient operation of thesystem.

Without the above implementation, there would be brought about thefollowing problems. The copier 1 has a remote informing function usingthe remote inform key and a remote informing function relating to anerror found by self-diagnosis. After receiving remote information, theCCU 18 sends the result of communication thereof with the control device16 to the copier 1 of interest. This allows the copier 1 to see whetherthe communication was successful or whether it was unsuccessful due tosome error. However, if the communication mode processing is maintainedvalid at all times, there will be indicated that the end ofcommunication is abnormal in the uncommunicable state. Moreover, sincethe item of remote diagnosis information can be displayed at all times,it may appear on the screen in an unexpected mode not supported by theoperator, confusing the operator.

In the illustrative embodiment, the communication mode processing isselectively allowed or inhibited depending on the connection condition(communicable or uncommunicable) of the copier 1 and CCU 18 and theON/OFF state of the switch, as stated above. Therefore, the programprocessing executing the communication processing is isolated from thecontrol of the copier 1, reducing the load on the CPU 100. This not onlyenhances efficient control but also invalidate the item of remotediagnosis information. As a result, information is prevented fromappearing on the screen in a mode not supported by the operator,promoting easy operation.

In FIG. 84, a step 2 corresponding to a case wherein while the copier 1and CCU 18 are in communication, the communication permit switch 116 ischanged from a permit state to an inhibit state. Should only the switch116 be operated to execute or inhibit the communication mode processingwithout awaiting the end of communication, it would invalidate thecommunication and result in a communication error. Specifically, whenthe switch 116 is ON as determined in a step 1 of FIG. 84, the step 2,i.e., a switch OFF subroutine is executed. Then, as shown in FIG. 86,whether or not the switch 116 has changed from an OFF state to an ONstate (edge trigger) is determined (step 40). If the answer of decisionis positive, Y, meaning that the switch 116 has been switched on,whether or not the copier 1 and CCU 18 are in communication isdetermined (step 41). If they are in communication, the communicationmode processing should not be inhibited and, therefore, it is continueduntil the end of communication (e.g. a signal EOF) has been detected(step 43). Thereafter, the program ends the communication modeprocessing and then returns.

In summary, it will be seen that the present invention provides acontrol system for an image forming apparatus having variousunprecedented advantages, as enumerated below.

(1) When the image forming apparatus is in an inoperative or waitingstate, data relating to image formation can be automatically down-loadedfrom a control device to the apparatus. This reduces the load on aserviceman and eliminates troubles ascribable to erroneous operations.

(2) The down-loading procedure is prevented from being interrupted.

(3) Data relating to image formation and matching a particular type ofimage forming apparatus can be automatically down-loaded from thecontrol device to the apparatus.

(4) Data can be down-loaded in or a flag can be read out of any one ofindependent areas each being used for a particular purpose. For example,a program may be written in a nonvolatile RAM to implement automaticversion-up. Also, a diagnosis program may be written in a DRAM foreffecting automatic diagnosis.

(5) The control device can automatically down-load data even whentimepiece means in the form of a weekly timer is not set.

(6) The period of time during which down-loading is not allowed isreduced.

(7) Down-loading can be effected at an adequate timing when the imageforming apparatus is in an ON state.

(8) The control device can down-load data to the image forming apparatusby a single access.

(9) Data can be surely down-loaded when the image forming apparatus isready to rewrite data.

(10) The control device is prevented from down-loading data to the imageforming apparatus while the apparatus is automatically adjusting imageforming conditions thereof.

(11) Also, the control device is prevented form down-loading data to theimage forming apparatus while the apparatus is likely to perform thenext image forming operation.

(12) Minimum necessary data can be loaded depending on the condition ofthe image forming apparatus.

(13) When a person stands by the image forming apparatus and is quitelikely to use it, the control device is prevented form down-loading datato the apparatus.

(14) In the event of up-loading data relating to image formation fromthe image forming apparatus to the control device, the load on theserviceman is reduced while erroneous operations are eliminated.

(15) In the event of up-loading data from the image forming apparatus tothe control device, data relating to image formation can be changed.

(16) The control device store data while identifying each image formingapparatus.

(17) When a memory is cleared, data relating to image formation can beautomatically down-loaded from the control device to the image formingapparatus to reduce the load on the serviceman.

(18) In the event of down-loading data from the control device to theimage forming apparatus, data relating to image formation can bechanged.

(19) There is eliminated an occurrence that an adjustment interruptedhalfway due to a communication is started all over again. As a result,the waiting time is reduced when a person is to use the image formationapparatus. Since the automatic adjustment is not interrupted, datarepresentative of adjusted image forming conditions are prevented frombeing destroyed and, therefore, image quality can be maintained withease. In addition, since the occupancy rate of a CPU due tointerruptions is lowered, the control system is simple.

(20) A person intending to use the image forming apparatus can start onthe operation immediately without waiting the end of a communication.

(21) Even when a communication is under way, the image forming apparatuscan be used immediately due to the interruption of the communication.

(22) Since data representative of adjusted image forming conditions arenot destroyed, safety data communication is enhanced to insure imagequality.

(23) The operator of the image forming apparatus can see that theapparatus is in communication although it is normal.

(24) Image forming modes can be surely registered at the image formingapparatus, and the waiting time is reduced.

(25) When a person desired to register image forming modes while acommunication is in under way, the person does not have to await the endof the communication.

(26) The system can be efficiently operated depending on whether or notthe image forming apparatus and a communication control unit arecommunicable.

(27) Even when the communicable/uncommunicable state of the imageforming apparatus and communication control unit changes while the powersource of the apparatus is in an OFF state, adequate and latest datarelating to such a state is recognized.

(28) The CPU is free from extra loads ascribable to the increase in thenumber of functions of the control system and the increase in processingspeed for image formation.

(29) When the image forming apparatus and communication control unitchange from a communicable state to an uncommunicable state, the changeis found by real-time detection. Hence, a procedure matching thecommunicable/uncommunicable state can be executed adequately andrapidly.

(30) When the communication control unit recovers from, for example, afault and sets up a communicable state, the recovery is detectedimmediately so as to validate a communication condition.

(31) Assume that the image forming apparatus and communication controlunit are not communicable, or that they are not connected by acommunication line. Then, a communication permit switch is operated toinvalidate a communication mode. This prevents a mode program forcommunication installed in the image forming apparatus from beingexecuted alone, thereby reducing the load on the CPU.

(32) When the communication mode function itself is not necessary, e.g.,when equipment with a communicating function is absent, the CPU of theimage forming apparatus is prevented from executing the communicationmode. This would otherwise increase the load on the CPU and, therefore,degrade efficiency.

(33) A change in the communicable/uncommunicable state of the imageforming apparatus and communication control unit, particularly a changefrom the communicable state to the uncommunicable state, is found byreal-time detection.

(34) Assume that a serviceman received a serviceman call comes to theuser's station for repair and performs a reproduction test of, forexample, a serviceman call. Then, needless data (e.g. a serviceman callsignal) is prevented from being sent by accident.

(35) The image forming apparatus and communication control unit can enda communication in a normal condition even when the communication permitswitch is operated while the communication is under way.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

What is claimed is:
 1. A system for controlling image formation,comprising:a plurality of image forming apparatuses each having astorage device containing data; a communication control unit connectedto said plurality of image forming apparatuses; a control deviceconnected to said communication control unit over a communication line,said control device interchanging said data stored in said storagedevices with said image forming apparatuses; said communication controlunit further including a parameter storing device having aninterchanging control parameter outputting said data and outputting asignal designating any one of said image forming apparatuses to beconnected to said communication control unit; and communication controldevice receiving and sending communication between said designated imageforming apparatus and said control device on the basis of the parameterstored in said parameter storing device.
 2. A system as claimed in claim1, wherein said parameter is written to said parameter storing devicefrom said control device via a public telephone network.
 3. A system asclaimed in claim 1, further comprising a parameter setting deviceremovably mounted to said communication control unit and allowing theparameter to be written to said parameter storing device thereon.
 4. Asystem as claimed in claim 1, wherein interchange of data between saidcontrol device and said communication control unit and interchange ofsaid data between said communication control device and said imageforming apparatuses are independent of each other.
 5. A system asclaimed in claim 4, wherein said communication control unit comprises amemory containing said data.
 6. A system as claimed in claim 5, whereinsaid control device reads said data out of said memory of saidcommunication control unit.
 7. A system as claimed in claim 5, whereinsaid control device sends data, including a parameter designating anyone of said image forming apparatuses, to said communication controldevice, while said communication control device accesses said designatedone image forming apparatus designated by said parameter.
 8. A system asclaimed in claim 1, wherein the parameter stored in said parameterstoring device is a number of times of redialing.
 9. A system as claimedin claim 1, wherein the parameter stored in said parameter storingdevice determine whether or not said data should be sent to said controldevice.
 10. A system as claimed in claim 1, wherein said image formingapparatuses are copiers.